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Team Sergeant
06-15-2015, 08:32
Lets discuss Rifle Accuracy

What are your rifle accuracy demands? (And yes we can split hairs all day concerning hunting, tactical use and bench rest.)
What is the furthest shot you might attempt hunting? What shooting positions are you most comfortable in? Is your rifle accurized? Do you hand load? Do you know how to measure the bullet ogive ? Do you know what the first focal plane refers to?

Most folks never heard of internal, external and terminal ballistics. A good definition here (http://fas.org/man/dod-101/navy/docs/swos/gunno/INFO6.html):

1. Interior ballistics is the branch of the science that deals with the projectile while it is still in the gun.

2. Transitional ballistics is the branch of the science that deals with the motion of the projectile from the time it leaves the muzzle until the only forces acting upon it are due to exterior ballistics.

3. Exterior ballistics is the branch of the science that deals with the projectile after it clears the muzzle and throughout its time of flight.

4. Terminal ballistics is that branch of the science that deals with the impact, and force imparted on the target.

(Transitional ballistics IMO is external ballistics. )



How far down this rabbit hole do you want to go? ;)

Brush Okie
06-15-2015, 09:06
How a bout rifle zero to start.

I prefer a 200 yard zero on most of my rifles. I usually use a 30-06 with 165 gr bullets for hunting. That will get me a head or neck shot flat enough out to 250 or so without having to hold over or under. Most of my kills are 100 yard range. With my load 200 yard zero is about 1.5 in high at 100 yards if that is all the distance I can zero at.

I know maximum point blank range is also a good method but to be honest I prefer 200 yard zero. It works well for me.

Than there is the 25 yard/Meter zero all Army folks have used. Well I can use it if no other choice but not my favorite.

:munchin

Papa Zero Three
06-15-2015, 10:11
Here's a good one. :)

https://youtu.be/hRAFPdDppzs

mojaveman
06-15-2015, 11:21
My favorite bangstick is a Winchester Model 70 Sporter XTR in .30-06. I also like the .243 because it has low recoil, shoots pretty flat and the deer in California are somewhat small.

Being that I don't reload and I am willing to buy decent ammo I am content getting 1.5 MOA accuracy with my rifles. I don't really like large objective variable power scopes and prefer using a 4X or 6X instead. MPBR with a 150gr projectile going 2900fps is about 285 yards so I don't think I would shoot any further than that.

I am most comfortable in the sitting position with both elbows resting on the knees. Other positions include standing with the right arm straight out parallel to the ground and the left arm supported on the chest. Prone supported is good too but you get dirty and see a lot less from down there.

The first thing I do with a new or used rifle is take it to the range. If it shoots decent I might not do anything. I usually then set the trigger at 4 pounds and sometimes bed the action or float the barrel.

I don't hand load because I just don't really shoot enough and as I stated earlier some of the factory ammo available is actually pretty good.

(1VB)compforce
06-15-2015, 16:33
Lets discuss Rifle Accuracy

What are your rifle accuracy demands? (And yes we can split hairs all day concerning hunting, tactical use and bench rest.)
What is the furthest shot you might attempt hunting? What shooting positions are you most comfortable in? Is your rifle accurized? Do you hand load? Do you know how to measure the bullet ogive ? Do you know what the first focal plane refers to?

Most folks never heard of internal, external and terminal ballistics. A good definition here (http://fas.org/man/dod-101/navy/docs/swos/gunno/INFO6.html):

1. Interior ballistics is the branch of the science that deals with the projectile while it is still in the gun.

2. Transitional ballistics is the branch of the science that deals with the motion of the projectile from the time it leaves the muzzle until the only forces acting upon it are due to exterior ballistics.

3. Exterior ballistics is the branch of the science that deals with the projectile after it clears the muzzle and throughout its time of flight.

4. Terminal ballistics is that branch of the science that deals with the impact, and force imparted on the target.

(Transitional ballistics IMO is external ballistics. )



How far down this rabbit hole do you want to go? ;)

Background:

Learned at 2ID Sniper while they were trying to get certified to be an official Sniper School (they never did get certified... remind me to tell you sometime about the HMMWV that probably ended their quest) I only hunt paper now. I loved the M21 system, but hated the Leatherwood ART II scopes because the elevation and magnification rings were aluminum and shaved each other.

Now my distance rifle is an AR-10 from DPMS (Panther Arms) that shoots <1 MOA from a cradle using Federal Gold Medal Match (FGGM). It's zeroed and confirmed at 300y using iron sights. No glass on it yet, I'll probably put a multi use scope like the Elcan w/ Dokter on it at some point. I use that distance out of habit, but should probably verify that the rise is the same as it was on the bolt actions.

To directly answer your questions:

I no longer have demands beyond the rifle being more accurate than I am. I don't ever like being in a position to blame the equipment for a miss rather than myself. It's my own fault I missed dammit!

I'd be confident of taking a shot out to 800-1000y against a non-moving target if I had a dope chart handy, but I don't hunt so haven't had the chance to make the call. (and I'm not sure how you talk the animal into standing still while I figure the windage :D). Against a live, potentially, moving target I'd probably shorten that to 400-500y with confidence as long as I didn't have to lead a runner.

I prefer prone supported or seated unsupported. I'm accurate kneeling, but never feel comfortable in it. Standing is my weakest for accuracy, especially in long strings. Seated I go cross legged and packed tight with the same arm positions as prone. I use my forward (non-shooting) elbow as a support rested on my left knee. Kneeling I rest my weight sitting on my rear foot/ankle with it crossed under me. Standing I do my best epileptic seizure imitation and try to time the pull :D

My rifle hasn't been bedded or accurized beyond the production specs. I'd love to go for an AI rifle sometime and see what I can really do now.

I don't hand load, I use FGMM. Never learned how and now, for killing paper, don't care. FGGM is good enough for any application I would use it for. I promise my personal accuracy isn't good enough any more for <.5 MOA variance to make a significant difference in my results.

Yup, but have no need to do so.

Yup maybe not the actual definition, but the practical use. First focal the reticle is magnified when the scope is adjusted, second focal the reticle stays constant. Changes how you range something using the scope. First focal can also obscure the target unintentionally at distance.

mark46th
06-15-2015, 18:56
My hunting rifle is a Model 70 in .270 Win that I bought at Walmart 10 years ago. I put a Nikon Buckmaster 3-9X40 scope on it. Best inexpensive scope I have ever found. I reload so for this one I use 140gr Barnes TSX bullets for pigs, mostly. My back up is a Rem 700 in .308. I use 168gr Barnes TSX bullets. It also has a Nikon Buckmaster. Both of these shoot 1MOA or better. I also have a Rem 700 in .338 Lapua Mag. It is on an AICS chasis, has a Timney trigger and S&B 5-25X56 glass. Load is Lapua brass with 300gr Matchking bullet and 92gr of Retumbo. It is zeroed at 600 yards. I haven't been able to group it due to there being no 800-1000 yard ranges locally.

HOLLiS
06-15-2015, 19:12
I do not bench rest any more so high accuracy is not practical for hunting or killing cannibalistic dirt clogs with their paper allies.

Hunting for elk, a gallon milk jug at 600M. A .338 Win Mag has about 2,000 ft pounds of energy at 600M. Good Elk Medicene

For Cowboy Action shooting, sufficient to hit the target.

IMHO, it depends on the needs of the shooter.

I use hand loads, IMHO more accurate than commercial loads.

My Ruger Mk II .308 on basic hand loads clover leafed at 100M.

I hate bi pods, either off hand, kneeling for hunting. Chicken wing works.

I do not measure ogive, I set bullet seating, where I have 0.030 free bore left, for long distant hunting.

I also use a Chrono to check bullet speed and chamber pressures. I prefer powder that burn a little slower with same bullet speed as one that burns a little faster.

I do fiddle with my main shooters for accuracy. My Mod 70 .338 Win Mag, is bedded (thought not needed for hunting), I recrown as needed. I like a trigger with a crisp release at about 2.5 pounds.

Furthers shoots off the bag with iron sights, 1000M. Hunting I am a lot more conservative. I am not into wound animals.

Focal plane............ I use two settings, for Mil dot 200M for others cone of accuracy where my POA/POI will be within the kill zone. Does not really answer your question. I rarely change magnification. Where I live there are not many long shots. So I adjust for those shots. At higher magnification I will, range my rifle before going hunting. (Range, adj POA/POI to the distance that I think I will be shooting, and use Kentucky windage to adjust as needed.)

Team Sergeant
06-15-2015, 21:17
I do not bench rest any more so high accuracy is not practical for hunting or killing cannibalistic dirt clogs with their paper allies.


I must admit, I've sent many of those "paper allies" to the great recycle center over the decades. No matter how many holes you punch in them they just seem to come back in greater numbers.

The fight continues......

Old Dog New Trick
06-16-2015, 01:05
Been reading this all day...don't have much to offer but wanted add something about "Transitional Ballistics" and the effects of those cool things at the end of the barrel or not.

Any gun/bullet can be more accurate than the shooter but some guns are better than others because of the way they let the bullet fly (Exterior Ballistics) or the last touch. Because after all, it's the last thing the gun can do well or not so much.

Barrel crown, be it standard round, 11-degree taper or recessed has a tremendous effect on how the gasses are expelled evenly around the bullet as it leaves the barrel and can ultimately affect flight. Is recessed better than tapered? I don't know but a cheaply finished crown or damaged crown will make even the best rifle junk.

Then there are all those things we screw onto the ends for various reasons: Flash Hiders, Muzzle Brakes, Compensators, and last but not least Suppressors. They all have an effect on the bullets "exterior ballistics" for better or worse.

Lastly, barrel length and twist rate for a given cartridge and powder charge. Some are too short, too long or too slow to adequately send the bullet down range properly. The end result is a loss of everything from accuracy to "terminal ballistic" effect. The wrong combination will make a great rifle bad or worse - unreliable.

Just my $0.02 to the discussion.

HOLLiS
06-16-2015, 01:08
I must admit, I've sent many of those "paper allies" to the great recycle center over the decades. No matter how many holes you punch in them they just seem to come back in greater numbers.

The fight continues......

My hope is, we will preserver against the deadly onslaught.

HOLLiS
06-16-2015, 01:15
Barrel crown, be it standard round, 11-degree taper or recessed has a tremendous effect on how the gasses are expelled evenly around the bullet as it leaves the barrel and can ultimately affect flight. Is recessed better than tapered? I don't know but a cheaply finished crown or damaged crown will make even the best rifle junk.



My two penny's worth.

Crown is all about concentric. Recess protects the crown where the bullet leaves the barrel. Off concentric crown will push the barrel this way or that. A pitted rifle barrel will not. The Crown will. IMHO, The Crown is a big part of accuracy. Bedding a rifle action is a very small part. In best rest, every 0.0001 improvement is a must.

When I re-crown, I like reset. It protects the crown.

We had three bran new mod 70s, One would not group. (1") Finally we recrowned it, and it was sub 1".

jw74
06-19-2015, 14:14
Any thoughts on the value of 'blueprinting' or truing the action?

I am curious if this is a gunsmith money-maker or an essential aspect to squeezing accuracy out of a rifle.
I have seen the change that a re-crowning can bring and wonder if blueprinting is the same.

I changed barrels to a different caliber on my hunting rifle and had it done at the same time so I can't say if the blueprinting was valuable but I suspect switching the factory plastic for a quality stock did more for accuracy than any other tweak.

Papa Zero Three
06-19-2015, 15:32
Any thoughts on the value of 'blueprinting' or truing the action?

I am curious if this is a gunsmith money-maker or an essential aspect to squeezing accuracy out of a rifle.
I have seen the change that a re-crowning can bring and wonder if blueprinting is the same.

I changed barrels to a different caliber on my hunting rifle and had it done at the same time so I can't say if the blueprinting was valuable but I suspect switching the factory plastic for a quality stock did more for accuracy than any other tweak.


Yes, it does make a OEM gun a lot better as everything is square and or trued up, something that doesn't happen on factory production built guns. If you're replacing a factory barrel, you might as well have the Smith true the action while it's apart as it's worth the few extra dollars.

longrange1947
07-05-2015, 09:38
Just to throw some crap out there, transitional ballistics is a form of external and is actually more pronounced in some barrel twists than others.

What it really effects is a near range zero. Remember that the bullet crosses the line of sight (LOS) twice, once on the way down range and when, hopefully your LOS and POI coincide on the target. With some barrel bullet combination, your grouping potential at say 35 meters is worse than your grouping potential at 200. Reason is Transitional Ballistics and this is when the effect of the rifle is still present and before only external forces effect the bullet.

Clear as mud? :munchin

Brush Okie
07-05-2015, 09:57
Just to throw some crap out there, transitional ballistics is a form of external and is actually more pronounced in some barrel twists than others.

What it really effects is a near range zero. Remember that the bullet crosses the line of sight (LOS) twice, once on the way down range and when, hopefully your LOS and POI coincide on the target. With some barrel bullet combination, your grouping potential at say 35 meters is worse than your grouping potential at 200. Reason is Transitional Ballistics and this is when the effect of the rifle is still present and before only external forces effect the bullet.

Clear as mud? :munchin

So at times a bullet will be less stable near the muzzle than farther down range? I have heard mixed opinions on this. Good to know. I read the 303 British Enfield supposedly did this but never heard this from a reliable source. Thanks

longrange1947
07-05-2015, 10:25
An ideally stabilized bullet is under spun at the muzzle, and when it gets to the intended accuracy range is properly spun. The bullet will become over spun at longer ranges.

In most bullet/barrel combinations, this is not an issue, but in some, the bullet "wobbles" around its flight path and the wobble becomes less and less until the bullet settles on that flight path. This causes problems with near range zeros.

The second problem is that the precursory column of air forms a mach disc that can upset some bullets. This requires the bullet to be over spun to maintain accuracy, another problem with transitional ballistics. :munchin

HOLLiS
07-05-2015, 12:28
So at times a bullet will be less stable near the muzzle than farther down range? I have heard mixed opinions on this. Good to know. I read the 303 British Enfield supposedly did this but never heard this from a reliable source. Thanks

IIRC, there is moment of destabilization when a bullet speed cross the the speed of sound. I believe more of a issue with people who shoot black powder.

Working on memory, so I may be off.

The transonic problem:

https://en.wikipedia.org/wiki/External_ballistics

Team Sergeant
07-05-2015, 12:53
Just to throw some crap out there, transitional ballistics is a form of external and is actually more pronounced in some barrel twists than others.

What it really effects is a near range zero. Remember that the bullet crosses the line of sight (LOS) twice, once on the way down range and when, hopefully your LOS and POI coincide on the target. With some barrel bullet combination, your grouping potential at say 35 meters is worse than your grouping potential at 200. Reason is Transitional Ballistics and this is when the effect of the rifle is still present and before only external forces effect the bullet.

Clear as mud? :munchin

Is this the reason (transitional ballistics) some have taken to "Barrel De-Resonators"?

GratefulCitizen
07-05-2015, 13:23
Not being a frequent shooter, I've looked at some of these accuracy issues from afar.
Curious as to what the sources of "error" are in accuracy.

Given several sources of error (call them e1, e2, etc.), statistical variation implies that the bigger sources dwarf the smaller ones to insignificance (at least until the bigger ones are reduced to near parity with the smaller ones through improved equipment, loads, etc.).
Total error = square root ((e1)^2 + (e2)^2 +...)

In the opinion of the experts, what are the biggest sources of error?

longrange1947
07-05-2015, 15:43
Trans sonic flight can be a problem due to the turbulence that can effect the bullet. This can be seen in the Ballistic Coefficient (BC) that, unlike published numbers, change through the flight of the bullet.

The BC decreases as the speed of the bullet decreases until trans sonic and it crashes. Once through to sub sonic it again climbs to the same level just prior to trans sonic or in many cases even higher.

The problems in bullet stability in some cases is not instability, but rather over stabilized gyroscopic problems. As soon as the bullet leaves the barrel the bullet becomes more and more gyroscopically stable. Reason is that while the MV slows, the spin rate does not slow hardly at all. This means that bullet is now becoming more and more like a gyroscope. And like a gyroscope, while hard to bump off its course, when bumped sufficiently it will do a radical change. The is where transonic can be a problem

Barrel de-resonators are an attempt to insure that the bullet comes out of the barrel at the exact same time in the barrel impulse. This increases accuracy. Most barrels, match barrels especially already do a pretty good job of that, but too many things can change the harmonics and change where the barrel is when the bullet exits. The De-Resonators are supposed to help fix that problem.

Biggest source of error? The shooter. Next is gun and ammo. Look at the statistical error of a .5 moa shooter, .5 moa gun, and a .5 moa ammo. Now change any one of them to 1 moa. Now change anyone of them to the normal hack shooter of 4 moa. Take a round and leave it in the chamber too long or out in the hot sun, you have induced an elevation error. Let the rifle set out in the sun to long and the top of the barrel heats more than the bottom. Top expands more that the bottom, elevation error. Get a crap gun and or crap ammo, and well, now you have errors compounded as the consistency is all over the map.

After that the biggest error, in rifle and long range, is air resistance. Be it wind, altitude, or whatever.

Still mud? I may be trying to answer is too short of a form. Let me know.

craigepo
07-05-2015, 18:36
I have two bolt guns that shoot really, really well. I also have a short distance, group therapy rifle. I'm thinking that I need more.

I'm thinking about getting, not necessarily an M21, but a highly accurate self-loader. .308 would be an acceptable caliber, as anything farther out would be bolt gun territory.

I have a friend who does a great job building bolt guns. He doesn't even touch autoloaders.

I'm curious if anyone has any expertise building such a rifle. What are the differences in building an accurate autoloader vs. a bolt gun? Can a person build an accurate self-loader while keeping the weight down to less than an M60?

HOLLiS
07-05-2015, 19:02
LR1947, I was told that Trans sonics was responsible for a anomaly with BP rifles. At 100M it has a 2 in group and at 200M is has 2 in group, after that it behaves normally after that.

Wasn't there some companies that would deliberately put a pressure point under the barrel? Other wise the barrel was free floating.


@ craigepo, Auto loaders as in the M1 Garand or the M14/M1A1?

longrange1947
07-05-2015, 19:29
Hollis, not trans sonic, your bullet is doing what the Brits call sleeping. It is what I was talking about above, if I have read your explanation correctly. The round is under spun to make it more accurate at your desired range. Brit Palma rounds are famous for this. The round is rotating around the flight path but not on the flight path, sort of a wobble. The bullet will slowly come back on flight path as the bullet slows and it becomes more gyroscopically stabilized. If a bullet was to go trans sonic while in that condition, the round would really take off due to the turbulence at trans sonic.

On the pressure point, that was for the lighter skinner barrels to prevent barrel whip. That is one of the reasons the SVD has such problems is simple barrel whip, well that and crap QC. The pressure point you can find right at the end of the fore stock in which the barrel rests on that pedestal. The heavier barrels do not have a barrel whip problem so the barrels are free floated. This gives about 17 pounds of up pressure and stabilizes the barrel so the bullet comes out of the barrel at the same point, or there abouts. :D

craige, how far out, I have shot my AR15 to 600 yards and have watched others shoot it to 1000 yards. The AR platform has really great potential. My OBR in 7.62 will shoot to over 1000 meters with no real problem. I would stay away form the M21/M1A platform unless you like messing around with a weapon keeping it tuned, and that is experience speaking.

GratefulCitizen
07-05-2015, 21:03
Biggest source of error? The shooter. Next is gun and ammo. Look at the statistical error of a .5 moa shooter, .5 moa gun, and a .5 moa ammo. Now change any one of them to 1 moa. Now change anyone of them to the normal hack shooter of 4 moa. Take a round and leave it in the chamber too long or out in the hot sun, you have induced an elevation error. Let the rifle set out in the sun to long and the top of the barrel heats more than the bottom. Top expands more that the bottom, elevation error. Get a crap gun and or crap ammo, and well, now you have errors compounded as the consistency is all over the map.

After that the biggest error, in rifle and long range, is air resistance. Be it wind, altitude, or whatever.

Still mud? I may be trying to answer is too short of a form. Let me know.

I understand how increasing the error from any one source dwarfs the other sources, especially when it comes to the shooter.
IIRC, TS once said something to the effect of "expensive golf clubs won't make you golf like Tiger Woods, neither will an expensive gun make you a good shooter".

Was curious as to some of the gun/ammo aspects purely from the technology standpoint, and what order of priority the experts would put on them.

There is just plenty of stuff in there that "I don't know that I don't know".
Trying to figure out what exists in those "blind" areas of ignorance.

At what point are there diminishing returns on barrel thickness?
How important are quality scope rings?
How important is parallax adjustment on optics?
Which aspect of handloading tends to matter most (precision in overall length, precision in powder charge, bullet choice, etc.) and why?
Should different bullet weights be selected to take advantage of the stability issues mentioned for different ranges?
It's my understanding that hollow points improve interior ballistics due to the rearward shifted center of mass.
-Is this true, and how important is it?
-Do hollow points suffer from less stability with exterior ballistics?

Those are a few of the thoughts wandering through my mind.

longrange1947
07-05-2015, 21:47
WOW, let me see if I can touch on these for you.

TS is absolutely correct, top gun will not make you a good shooter, but it will prevent a good shooter from shooting rat shit in a dresser drawer.

Weapon/optics

Barrel, needs to be heavy enough to not whip but not so heavy as to be unwieldy. Forget flutes, they are a way to make money for the gunsmith. The barrel on the M24 is about the limit on thickness and that is pushing it a bit. The bore needs to be enough to have a good throat but not so new as to have not settled in, a reason for the first 100 - 150 rounds. Once the throat starts to erode you have problem with free bore but you do not want to pre-engrave the bullet by making the throat too tight. That horse is dead, it also leads to making it so tight that the care becomes pre-engraved, which in turn pinched the bullet and you get one hell of a pressure spike, not good for gun or shooter, let alone accuracy.

Barrel needs to be free floated and allowed to vibrate from the round and explosion that just took place. The ideal situation is that the barrel harmonics allow the round to exit the barrel in the same point of the sin wave. I use sin wave loosly here, as the wave can be on any plane around the barrel and in some cases loops around the barrel as the bullet spins down the barrel. This error is measured in MOA and is more pronounced as the range increases. Anything, and I mean anything that disrupts this harmonic will cause a loss of accuracy. This is usually a shooter error that allows the barrel to become trapped and not vibrate freely.

Action and recoil lug needs to be fixed, usually by bedding and only the rear of the recoil lug will touch the bedding/stock. If the action begins to shift in the weapon due to collapsing bedding, crushed wood/fiberglass, then as the action shifts so does the alignment of the barrel.

Stock needs to fit the shooter so that he can get a natural stock/spot/cheek weld. This sets the eye relief which sets the sight alignment. Sight alignment errors are measured in MOA and as with above becomes a greater miss at longer ranges. Sight alignment plays in scopes as with iron sights, when you do not have a parallax adjustable scope.

Scope rings, buy good ones, cheap ones will loosen or break at the worse possible time, and will not hold zero or will not return to zero if the scope needs to be removed. An example is the Redfield ring/base combo on early SWSs. The scope rings were not fixed well in the base and the rings would begin to drift.

Parallax error is measured in MOA but to see the actual error, look through the scope and wiggle your head, when you see the cross hairs move from one side of the target to the other, and off the target, that is your potential error. Very important. When we did not have parallax adjustments, I would wiggle my head and make sure that I not only did not have shadow, parallax indicator that your head is not aligned properly, but that the reticle moved evenly left right up and down on my target, took a second, but helped negate the error.

Handloading is all about consistency. All cases should weigh the same. Why, because a difference in weight means that there is a difference in case capacity which means there will be a pressure differential. That pressure change is a MV difference. Also, powder charge needs to be trickled to the correct weight, again MV changes if you have a change in powder weight. There are so many little things in handloading that will bite in when you are looking to accuracy. From touch hole being clean and concentric for even powder burn to case length for the same free bore shot after shot.

Bullet weights are important, I shot 77gr for 200 and 300 yards, and 80gr for 600 and 1000. Most people shoot the round that gives them best overall. Along with that bullet weight is the powder charge for the different bullets, of course I had more powder for the 80gr and wanted a round moving to buck the wind, for the 77gr I lowered the powder for not only the bullet, but so that during rapid fires my sights would not leave the bullseye.

Ballistic hollow points were originally made by swagging the bullet from the rear and drawing the copper gilding to the point. This created a bullet with less turbulence in the rear and thus less drag. Through experimentation and never letting things stay too stagnant, several of the bullet manufacturers moved to a plastic tip to move the CG more to the rear. This helped in some things and hurt in others. When a bullet becomes over stabilized it acts as a gyroscope. When this happens as the bullet falls back to earth it will still stay nose high due to the over stabilized bullet. This leads to other problems when wind, pressure changes, etc hit. It also is the leading cause of key holing besides shooting the berm.

A rearward shift would not effect interior ballistics, but the VLDs and semi bore ridding bullets does and they are finicky as hell due to it. I would leave them out of the mix unless you are very good at reloading. The rearward shift can effect exterior ballistics especially in the case I sited above where the bullet starts flying butt low/nose high.

That should get you started. Let me know if I can answer more questions and if these help. When you start to talk about extreme long range, then a whole new set of problems set in to include the rotation of the earth. :)

GratefulCitizen
07-05-2015, 22:18
Thank you LR.
I find the physics of this stuff fascinating.

<edit>

Another question:

The Nosler partition bullets would tend to have slightly more mass distributed to the front and rear than a conventional design.
While this would not change center of mass, it affects angular momentum along the longitudinal axis relative to bullet mass.

Looking at the math, this would have an effect on reducing wobble while in flight.
Would the effect be neglible?

PRB
07-05-2015, 22:50
I like a swamped barrel with round rifling and a relieved crown for easy loading.

mark46th
07-06-2015, 09:51
Craigpo- My son has a flat top AR10 in .308. The snipers in his agency took it to the range and said that it shot as good as or better than their bolt guns. It has a 20" bull barrel and some trigger work. The scope is a Leupold Mk4 4.5-14X40.

pcfixer
07-06-2015, 10:27
WOW, let me see if I can touch on these for you.

TS is absolutely correct, top gun will not make you a good shooter, but it will prevent a good shooter from shooting rat shit in a dresser drawer.

Weapon/optics

Handloading is all about consistency.


Many very good points, LR! As a handloader for many years I do understand all dynamics and consistency problems of loading many 06, 243 and now 5.56 ammo.
I also load my own 45 Auto, 45 LC ammo. I enjoy this port, sometimes get a little frustrated over the shooting ie bullets don't hit the target consistently in a group. I've learned guns sometimes don't like a particular powder or bullet to be accurate for me.

Also after replacement of 06 barrel with a Douglas XX Premium barrel, Bell & Carelson Stock that is bedded there is still some inconsistency. After a few phone calls to Douglas I found more of the science of barrel whip or vibration.
http://www.stocks-rifle.com/harmonics.htm

From this I gather that each gun has it's own 'sweet spot' for ammo that is being shot. Being a hand loader it takes a number of trips to the range.

Guymullins
07-06-2015, 11:01
I was looking at a Rigby .416 a couple of days ago. The new Rigby company is back in England, making handmade rifles which are based on the original Rigby's of old.

They are crazy expensive, although not in the Holland&Holland league, but I always fancied one as it is a caliber I greatly respect, and getting it in a Rigby is the cherry on top.

With the rifle, came a sample target and I was shocked to see that it was marked as shot over 65 yds and the group was well over three inches. This put me off the rifle and the company completely as I consider that unacceptable accuracy for any rifle, apart maybe for a double, but even then, I would be disappointed. My Remington .375 will shoot to a half inch over that distance and I question a manufacturer who would proudly include a target showing that kind of accuracy for a very expensive gun. The old Ruger .416 Rigby I have shot with in the distant past would beat that hands down and cost one tenth the price.

Rob_Frey
07-06-2015, 18:39
I like a swamped barrel with round rifling and a relieved crown for easy loading.

Whitworth?

jw74
07-08-2015, 11:20
I was looking at a Rigby .416 a couple of days ago. The new Rigby company is back in England, making handmade rifles which are based on the original Rigby's of old.

They are crazy expensive

it was marked as shot over 65 yds and the group was well over three inches. This put me off the rifle and the company completely as I consider that unacceptable accuracy for any rifle, apart maybe for a double, but even then, I would be disappointed. My Remington .375 will shoot to a half inch over that distance and I question a manufacturer who would proudly include a target showing that kind of accuracy for a very expensive gun. The old Ruger .416 Rigby I have shot with in the distant past would beat that hands down and cost one tenth the price.

I'm guessing that they are touting the handmade 'old-world' aspect of the rifle and holding the current desire for ultra-accuracy in disdain and perhaps unneccesary when their rifle is meant for something cape buffalo-sized at 30 yds.
I'm with you though. If all I wanted was an old, heavy, inaccurate rifle I wouldn't compund the problems by emptying my bank account also.

Was the target you saw shot off hand?

Guymullins
07-08-2015, 15:14
I'm guessing that they are touting the handmade 'old-world' aspect of the rifle and holding the current desire for ultra-accuracy in disdain and perhaps unneccesary when their rifle is meant for something cape buffalo-sized at 30 yds.
I'm with you though. If all I wanted was an old, heavy, inaccurate rifle I wouldn't compund the problems by emptying my bank account also.

Was the target you saw shot off hand?

That information was not available, but why would a manufacturer even include a target if it were shot offhand with iron sights? Mind you, iron sights at 65yds should still give better accuracy than that.

HOLLiS
07-08-2015, 18:03
I was looking at a Rigby .416 a couple of days ago. The new Rigby company is back in England, making handmade rifles which are based on the original Rigby's of old.

They are crazy expensive, although not in the Holland&Holland league, but I always fancied one as it is a caliber I greatly respect, and getting it in a Rigby is the cherry on top.

With the rifle, came a sample target and I was shocked to see that it was marked as shot over 65 yds and the group was well over three inches. This put me off the rifle and the company completely as I consider that unacceptable accuracy for any rifle, apart maybe for a double, but even then, I would be disappointed. My Remington .375 will shoot to a half inch over that distance and I question a manufacturer who would proudly include a target showing that kind of accuracy for a very expensive gun. The old Ruger .416 Rigby I have shot with in the distant past would beat that hands down and cost one tenth the price.


Accuracy is related to the need. As JW pointed out 3 In group at 65 yards is good medicine for cape buffalo.



BTW before I forget.

LR9147, thank you for your contributions to this thread.

longrange1947
07-09-2015, 10:20
That Rigby was an "Elephant Gun" with tremendous pressures that required a large free bore. That is what effects the accuracy and as Holli stated, at less than 100 yards at a Cape Buff, Hippo, or an Elephant you have the accuracy needed and the the power required to save your butt. Weatherby has the same accuracy in their large bore weapons and again due to free bore due to the pressures.

Hollis, my pleasure. At you guys service when I can help.

Guymullins
07-09-2015, 16:17
[QUOTE=longrange1947;587309]That Rigby was an "Elephant Gun" with tremendous pressures that required a large free bore. That is what effects the accuracy and as Holli stated, at less than 100 yards at a Cape Buff, Hippo, or an Elephant you have the accuracy needed and the the power required to save your butt. Weatherby has the same accuracy in their large bore weapons and again due to free bore due to the pressures.



The .416 Rigby is designed to quite low pressures. 47 000psi compared to the .375 H&H at 62 000 psi. The .416 Weatherby is 63 000psi.
So I don't think chamber pressures can really be blamed for the poor accuracy of the Rigby rifle. The CZ 500 made for the .416 Rigby round, which costs a fraction of the Rigby rifle, shoots a standard 1.5 inch group at 100yds and often much better than that. The CZ is very popular here in Africa as it is great value for money and makes a good workhorse.

Extreme accuracy is not needed for the average Buff or elephant hunt, however, many African hunters like to carry one rifle to do everything. Thats why my everyday rifle is a .375 H&H. When going out to shoot an Impala for the pot, one can come across an angry buff or jumbo, so selecting a rifle for a specific hunt is not always the wisest thing to do. Naturally, if you have the money to engage a PH who can carry a big bore, you can then traipse out with your 30-06 without any worries.

longrange1947
07-09-2015, 17:44
I stand corrected. Several articles I had read on the old guns grouped the Rigby with the other "Elephant guns", H&H and Weatherby, with higher pressures and reduced accuracy.

I bow to your experience in lieu of my readings. :)

Guymullins
07-10-2015, 09:50
I stand corrected. Several articles I had read on the old guns grouped the Rigby with the other "Elephant guns", H&H and Weatherby, with higher pressures and reduced accuracy.

I bow to your experience in lieu of my readings. :)

You are right with respect to some of the early Elephant calibers. The old propellants were fine when used in England and America, but when subjected to the extreme temperatures of tropical Africa, they developed very high chamber pressures which in turn split cases or made extraction impossible or difficult. Not something hunters were enamored with when hunting dangerous game. For instance, the .458 Win Mag, based on a straight-sided .375 H&H case got a very bad reputation in Africa because they were downloaded by Winchester to avoid excessive pressures in the tropics and thereby delivered sub-standard performance.
Older bullet performance was also unsatisfactory in some of the first Express and Magnum rounds. Rigby gained a great reputation with its .416 round not only because of its gentle pressures but perhaps more importantly, because its patented bullets had very thick steel walls and tips and a well crimped rear which held the led in place and didn't deform badly when penetrating elephant sculls and buffalo shoulder bones. The bullet paths were straight and went further than other bullets through solid flesh and bone.
The .458 Win Mag's reputation is only now recovering, due to modern powders combined with modern bullets, but various higher performing .458 variants are still very popular such as the .458 Lott and Ackley rounds which attempt to cure the round of its old illnesses.

frostfire
07-25-2015, 08:36
Hollis, not trans sonic, your bullet is doing what the Brits call sleeping. It is what I was talking about above, if I have read your explanation correctly. The round is under spun to make it more accurate at your desired range. Brit Palma rounds are famous for this. The round is rotating around the flight path but not on the flight path, sort of a wobble. The bullet will slowly come back on flight path as the bullet slows and it becomes more gyroscopically stabilized. If a bullet was to go trans sonic while in that condition, the round would really take off due to the turbulence at trans sonic.

Is this the reason, 147gr coming out of my slow-twist 1:32 KKM barrel resulted in key holing at 25m?
I almost wanted to leave it like that so that tiny 9mm diameter would make elongated holes to reach those x and 10 lines:D



On the pressure point, that was for the lighter skinner barrels to prevent barrel whip. That is one of the reasons the SVD has such problems is simple barrel whip, well that and crap QC. The pressure point you can find right at the end of the fore stock in which the barrel rests on that pedestal. The heavier barrels do not have a barrel whip problem so the barrels are free floated. This gives about 17 pounds of up pressure and stabilizes the barrel so the bullet comes out of the barrel at the same point, or there abouts. :D
.

Is this the reason I found my 10.5" short barrell AK yields better accuracy than the standard 16" pencil barrel one? I mean better/closer pressure point to the action without much length left for any vibration?

Master Rick, always good to see you back in your element :)

Leozinho
07-25-2015, 21:42
An ideally stabilized bullet is under spun at the muzzle, and when it gets to the intended accuracy range is properly spun. The bullet will become over spun at longer ranges.

In most bullet/barrel combinations, this is not an issue, but in some, the bullet "wobbles" around its flight path and the wobble becomes less and less until the bullet settles on that flight path. This causes problems with near range zeros.

The second problem is that the precursory column of air forms a mach disc that can upset some bullets. This requires the bullet to be over spun to maintain accuracy, another problem with transitional ballistics. :munchin

For what it's worth, Bryan Litz and his partner Nick Vitalbo (http://appliedballisticsllc.com/about-us/staff/) have done some tests that don't support the theory of a bullet going to sleep as the reason why group size at longer distances are often better than what would be extrapolated from group sizes at shorter distances.

Litz thinks it's using an effectively smaller aiming point at longer distances that produces better groups at distance. Vitalbo thinks its because it's easier to dial out parrallax at longer distances.