Multi-purpose rifle

[Justinmd]

Gents,
Recently a SOTIC instructor mentioned the desire for a rifle similar to an SR-25 (precision semi-auto .308), but with a collapsible buttstock and a shorter barrel (perhaps under 20") that could be used for assault if needed. Is this something you would find useful? If so, how would you spec it out?

1. Barrel Length (and/or desired effective engagement range)?

2. Weight (would you sacrifice a thick meaty barrel for more portability)?

3. Caliber cababitly (is .308 and its variants good enough or does it need to take the short mags as well)?

4. If it came with two barrels, say an 11" for DA and a 22-24" for long range precision, would you switch them out for different missions or just keep a medium length (16-20")barrel on all the time.?

5. Optic, what would you prefer for this type of setup.?

Ok thanks for the help gents. If all goes well, you may see something at SHOT show.
Justin

[jatx]

I'd just offer some thoughts after having played with (and spent money on) this idea for awhile. I invested in just such a project about 18 months ago, and had John Noveske build me one of his Leonidas rifles. The thread with pics and full specs is here:

http://www.professionalsoldiers.com/...=10252&page=28

With 168 gr. Federal GMM, the muzzle velocity is about 2650 fps and the maximum PBR is roughly 325-330 yards. I use a Nightforce 1-4x optic in a Larue mount, which sits about 2.75 inches above the bore axis.

If I were to limit the engagement range to "assault" distances, I would need to hold low 2.5-3 inches with a 100 yard zero. That seems a little strange for someone used to shooting 5.56 all the time, but I'm sure training could make up for it. At 200 yards, bullet drop is 3 inches and at 300 yards it is roughly 13 inches. My ballistics software tells me that at 300 yards the muzzle velocity has dropped to approx. 2075 fps and energy to 1620 ft. lbs. I'll let you judge for yourself whether or not that is acceptable for your purposes, but IMVHO 11" is too short and will greatly impact the above ballistics, which are already a compromise.

Despite the loss of velocity and energy, I have experienced no loss in accuracy with the short barrel. However, if I were building another rifle geared towards smacking two-legged predators and thin skinned game at ranges from contact to 350 yards, I would go with a 16" upper in 6.8 SPC. My rifle and its ammo are pretty porky, and I would dislike humping them long distances. The 6.8 would avoid both problems and allow me to use a single lower with one stock, grip, sling, etc.

Also, despite people's tendency to complain about muzzle blast, I would not get a Krink-style FH again. It adds too much weight to the front of the weapon and does nothing for recoil reduction. Using a low power variable optic like the Nightforce, which is wonderful but has a 1.5 MOA center dot and a limited field of view on 4x at 300 yards, I would go with the PWS FSC in either .308 or 6.8. IMHO, it is much more important to get follow-up shots on target quickly than it is to mitigate blast in the rare instances where you might shoot this thing inside.

[The Reaper]

Originally Posted by jatx

Also, despite people's tendency to complain about muzzle blast, I would not get a Krink-style FH again. It adds too much weight to the front of the weapon and does nothing for recoil reduction. Using a low power variable optic like the Nightforce, which is wonderful but has a 1.5 MOA center dot and a limited field of view on 4x at 300 yards, I would go with the PWS FSC in either .308 or 6.8. IMHO, it is much more important to get follow-up shots on target quickly than it is to mitigate blast in the rare instances where you might shoot this thing inside.

Good points, but try getting quick follow-up shots with a shorty 7.62 at night without a flash suppressor.

I think you will see the utility of it.

A can is even better.

TR

[Tuukka]

Originally Posted by The Reaper

Good points, but try getting quick follow-up shots with a shorty 7.62 at night without a flash suppressor.

I think you will see the utility of it.

A can is even better.

TR

TR,

[jatx]

Very nice, Tuukka, how does she shoot?

[Justinmd]

Thanks for the info so far fellas. The weight and portability won't be a problem like on an AR-10. The size will be only slightly larger than a 5.56 platform (longer by a bit). Also it will be largely polymer and Al so should be fairly light.
I have designed a muzzle brake that I'm going to try, to keep recoil down, that has a provision to reduce muzzle blast to the sides and rear (for shooting in a room next to your buddy). I'm not sure how it will work, but it could solve that problem. Right now we're looking at both a shorty barrel and a long barrel at 18-20. The barrels are quick detach so switching is pretty easy. I'll have to run some ballistics and see if there is much range difference between 18 and 20". The new Iron Brigade Armory bolt action sniper rifle has an 18" barrel and they claim 800yd capability, if I remember correctly. I'd love to hear more thoughts on this. Thanks,
Justin

[HOLLiS]

Justinmd,

Have you seen the GI issued muzzel brake for the M14? It is was detachable and fitted over the flash suppressor. It has a catch that slid back and locked on the bayonet lug. I think I picked mine up from Numrich. It might be worth looking at in designing a adjustable brake.

[Justinmd]

Thanks for the heads up. I'll have to check that out. It could save me some trouble,
Justin

[That Guy v2.0]

Originally Posted by Justinmd

Gents,
Recently a SOTIC instructor mentioned the desire for a rifle similar to an SR-25 (precision semi-auto .308), but with a collapsible buttstock and a shorter barrel (perhaps under 20") that could be used for assault if needed. Is this something you would find useful? If so, how would you spec it out?

1. Barrel Length (and/or desired effective engagement range)?

2. Weight (would you sacrifice a thick meaty barrel for more portability)?

3. Caliber cababitly (is .308 and its variants good enough or does it need to take the short mags as well)?

4. If it came with two barrels, say an 11" for DA and a 22-24" for long range precision, would you switch them out for different missions or just keep a medium length (16-20")barrel on all the time.?

5. Optic, what would you prefer for this type of setup.?

Ok thanks for the help gents. If all goes well, you may see something at SHOT show.
Justin

At the risk of moving to far out of my lane....If you get a chance check out this thread:

http://professionalsoldiers.com/foru...ad.php?t=15765

Thread originator is another QP Longrange1947 that has hands on experience with a system that may fit your needs.

The system is the LWRC Sniper Assaulter Battle Rifle (SABR). It is a .308 piston driven rifle in an AR configuration that takes the SR25 mags with available barrel lengths of 16" or 20". It will supposedly be available after Shot Show 2008.

For more detailed info check these:
http://www.lwrifles.com/forum/viewtopic.php?t=1278
http://www.lwrifles.com/forum/viewtopic.php?t=6

It will also be in one of this season's episodes of Future Weapons along with other LW products:

http://www.lwrifles.com/forum/viewtopic.php?t=527

Full Disclosure:
I am in no way affiliated with or have any financial interest in LWRC.

[Gene Econ]

Originally Posted by Justinmd

Gents, Recently a SOTIC instructor mentioned the desire for a rifle similar to an SR-25 (precision semi-auto .308), but with a collapsible buttstock and a shorter barrel (perhaps under 20") that could be used for assault if needed. Is this something you would find useful? If so, how would you spec it out?

1. Barrel Length (and/or desired effective engagement range)?

2. Weight (would you sacrifice a thick meaty barrel for more portability)?

3. Caliber cababitly (is .308 and its variants good enough or does it need to take the short mags as well)?

4. If it came with two barrels, say an 11" for DA and a 22-24" for long range precision, would you switch them out for different missions or just keep a medium length (16-20")barrel on all the time.?

5. Optic, what would you prefer for this type of setup.?

Ok thanks for the help gents. If all goes well, you may see something at SHOT show. Justin

Justin:

You have no choice with what you are describing but to go with a AR-10 or SR-25 with all of its bulk and weight. Do you want a 7.62 based cartridge rim or not is the question. If you do, accept the weight and bulk of an AR-10 or accept shearing bolt lugs.

I was firing a JP 18" .308 upper on an AR-10 lower for the last couple of days and even though it had an exceptional compensator, the recoil was quite significant when firing issued M-118 Long Range ammunition. John Paul's compensator did reduce recoil but it would blow out a fellow's ear drums he he was standing next to the muzzle when fired.

You haven't yet given any really good physical criteria to detail your requirements. Such as penetration through a specific medium, engagement ranges for such penetration, terminal effects on the human body, etc.

IMHO -- you are asking for somthing bigger than the 5.56 but smaller than the 7.62. A issued service load in 7.62 NATO is pretty stiff -- M-118 or M - 80 Ball.

OK --- there are two relatively available cartridges that give you perhaps what you want and from an AR-15. The 6.8 and the 6.5 Grendel. There are also .30 caliber cartridges that are used with the AR-15 aside from the 7.62X39 but these cartridges are still pretty much wildcats.

Of the 6.8 and the 6.5 Grendel, one uses a bullet that is better in terms of teminal effects and one is better in terms of exterior ballistics to 350 yards which is what you said was your engagement range. Both have less than half the felt recoil of a full size SR-25 or AR-10 without compensators or muzzle breaks and both can be shot from the issued AR platform which is smaller than the AR-10 / SR-25 platform.

I prefer the Grendel believe it or not because I believe it offers a higher hit probability at ranges from 300 - 600 and IMHO if you put a 120 grain bullet into someone at 500 yards for example, it will put more kinetic energy into that person than a 63 grain, tungsten tip, 5.56 bullet at a lesser velocity (at that range) .

Both the 6.8 and 6.5 Grendel are high pressure cartridges for the AR platform and both will blast someone at ten yards as well as the other with half the recoil and at least 70% less blast than a carbine firing an issued 7.62 round.

It is my opinion that both the 6.8 and 6.5 Grendel will kill someone as readily as each other at ranges to 300 yards. However, my bets are on the Grendel in terms of hit probabilities at any range from 300 - 600 yards over either the issued 7.62 LR or M-80 or any loading of the 6.8 when fired from any platform while under stress.

I know why I say these things and won't get into someones pissing contest so you Grendel or 6.8 'Bots' out there -- if you think I care about your prejudices then think again.

That ought to stir the pot for you some. Maybe others have solid views too and that is how you will learn what is needed.

Gene

[The Reaper]

Gene:

Good advice, but don't count on finding a lot of 6.8 or 6.5 Grendel in the AO if you did not bring it with you.

TR

[Peregrino]

Gene - Funny you should open the 6.5/6.8 "can of worms" again. Solid argument from the ballistics perspective but not much else to recommend either one as a practical military solution. My gunsmith and I have been playing with rebuilding AKs ($750 worth of parts, etc. to have a $350 rifle - not counting what the "smithing" services are really worth ) for entertainment/education. (They make a fun "truck gun".) He's actually decided to put one together in 6 or 6.5 PPC just to prove the point. We discussed the 6.8 but I haven't checked for magazine compatibility. Too much fun tinkering on winter afternoons.

[Sinister]

Armalite makes a select-fire 7.62 carbine that for all intents and purposes is a 7.62mm M4. The barrel is a lighter profile (very close to the original M14 taper).

DPMS also makes a comparable carbine they call an AP4 I think.

The SR-25K is a piece of shit in my very limited experience and my singular personal opinion.

HK used to make a shortened G3-style carbine (HK 51?).

[longrange1947]

Originally Posted by Sinister

Armalite makes a select-fire 7.62 carbine that for all intents and purposes is a 7.62mm M4. The barrel is a lighter profile (very close to the original M14 taper).

DPMS also makes a comparable carbine they call an AP4 I think.

The SR-25K is a piece of shit in my very limited experience and my singular personal opinion.

HK used to make a shortened G3-style carbine (HK 51?).

There are actually quite a number of weapons out there now.

As far as the SR-25K, I rank it with the rest of Knight's junk.

As far as the 6.5/6.8 controversy, unless it is developed to the point where I go to Joe blow and get ammo from him them you will eventually have a club instead of a rifle. Give it only to the Spec Ops, as has been mentioned before, and you have a signature round. All bad.

Heck Gene, there are a bunch of ballisticlly superior rounds out there, but they are not compatible with other systems and that severely limits ammo distribution or becomes a signature round. Or there are other sever draw backs such as barrel life.

My 2 cents.

[Gene Econ]

Originally Posted by longrange1947

There are actually quite a number of weapons out there now. As far as the 6.5/6.8 controversy, unless it is developed to the point where I go to Joe blow and get ammo from him them you will eventually have a club instead of a rifle. Give it only to the Spec Ops, as has been mentioned before, and you have a signature round. All bad.

Heck Gene, there are a bunch of ballisticlly superior rounds out there, but they are not compatible with other systems and that severely limits ammo distribution or becomes a signature round. Or there are other sever draw backs such as barrel life. My 2 cents.

RB:

Not pushing either cartridge and not trying to start debates over them. The individual mentioned an intermediate cartridge and of them all, it seems those two have gotten the most attention.

I personally have no stake in this game as it ain't my life that will depend on it but I do commend guys who finally realize that the fastest way to lower recoil and a smaller overall weapon is probably a smaller cartridge.

So lets see who pops up for TR to blast! He, he, he.

Gene