zeroing problems

[fng13]

I just purchased a 1" Burris P.E.P.R. mount and a 4-16x-42sf Nikon Monarch scope combination for my ar-15. I took it to the range today to zero it. At 25 yards I got an almost correct zero but I used all of the right adjustment. The mount is one peice so I am unsure how I would have got it out of alignment. I was careful to tighten the the rings down equally. After levelling the scope, I snuged up the rings before using 5 in/lbs on the front ring first then moved to the back ring. I then repeated this to 10 in/lbs. I suppose I could have mounted the entire mount incorrectly somehow by overtightening it, but I only hand tightened the mount screws.

Anyone have any suggestions or may have experienced this?

thanks,

Fng13

[Gene Econ]

Originally Posted by fng13

I just purchased a 1" Burris P.E.P.R. mount and a 4-16x-42sf Nikon Monarch scope combination for my ar-15. I took it to the range today to zero it. At 25 yards I got an almost correct zero but I used all of the right adjustment. The mount is one peice so I am unsure how I would have got it out of alignment. I was careful to tighten the the rings down equally. After levelling the scope, I snuged up the rings before using 5 in/lbs on the front ring first then moved to the back ring. I then repeated this to 10 in/lbs. I suppose I could have mounted the entire mount incorrectly somehow by overtightening it, but I only hand tightened the mount screws. Anyone have any suggestions or may have experienced this? thanks, Fng13

FNG:

I doubt the optic is screwed up or the mounts as that is a lot of windage you are dealing with.

Check first that the mount is put on the rail properly. Sometimes a guy turns the little side latch upwards when tightening and this causes the front or rear of the mount to shift left or right.

If that is OK then put the rifle without the optic in a cradle and look directly down at the rifle and see if the barrel is pointed to the left in relation to the flat top of the upper. If the barrel in fact is out of alignment with the flat top of the upper either the upper was poorly made or most likely the barrel wasn't installed properly.

If you note nothing then put the optic and mount back on the upper, tighten it down agan and do the same thing this time using the optic as a reference. Look to see if the optic is pointing right or left in terms of the barrel. If so, the mount was poorly made.

With that much windage you would see visually a difference in alignment between the barrel and upper and or the barrel and optic. It will be very evident one way or the other.

If neither show any misalignment, your Nikon optic is screwed up.

Gene

[fng13]

Thanks for the advice!

I took the optic and mount off and looked down and I don't think that it is pointing to the left if it is it is not very apparent. I will conceed though that only about 3-4 inches of the barrel protrudes from my rifle length Troy trx rail so I can't really follow the length of the barrel down. I don't have the tools here to take the rail off or I would. Its a little bit of a pain. To put the rail system on required the removal of the original barrel nut and the installation of Troy's proprietary nut. I did this myself but at no time did i move the barrel the old nut came off and the new on. I did it in a vice. The blocks I use hold the upper in sideways though, would the barrel have angled to the left if no nut was on? I'm positive i would have noticed this if that happened. I looking down the top of the rail is still doesn't appear to be angled left.

I then put the scope and mount back on and it also appears to be in line.

Is it likely to be the scope? I just bought this from a dealer on amazon. It is brand new.

Im not sure if this is relevant but the scope was consistent when I shot it today. By consistent I mean I could hold off the bullseye in the same way each time and hit it no problem. If the optics were screwed up would this be possible.

Also, I am left handed could it be possible that the way I am looking through scope is making me have to shift it more to the right? It seems unlikely though because I shot with my off hand with exactly the same result.

Thanks for the help, this is disappointing.

[Peregrino]

You have an alignment problem (I know; belabor the obvious!). If the weapon zeroed with the previous handguard, I'd check the barrel nut first. Otherwise it's in the mount. Find a competent gunsmith. Nothing to be hesitant about; they make their living fixing problems like yours. They only charge extra if you persist in screwing with it after you realize you're in over your head. (Yes - I'm pretty good, but my gunsmith still takes my money regularly!) Good luck.

[longrange1947]

Originally Posted by Peregrino

You have an alignment problem (I know; belabor the obvious!). If the weapon zeroed with the previous handguard, I'd check the barrel nut first. Otherwise it's in the mount. Find a competent gunsmith. Nothing to be hesitant about; they make their living fixing problems like yours. They only charge extra if you persist in screwing with it after you realize you're in over your head. (Yes - I'm pretty good, but my gunsmith still takes my money regularly!) Good luck.

I agree with this completely. The barrel is out of alignment from the nut change over. Good gunsmiths may cost but they do get the job done right the first time. That is why I use them and do not do that myself.

[mojaveman]

I'd send the scope back and try another one.

[fng13]

Originally Posted by Brush Okie

What type of rings are you using? Are they cheap rings? If so they may be the problem. Also are they the type you only tighten one side or both sides? Do you have some photo's. That might help.

I am using the burris P.E.P.R. Mount, it is a single mount with 2 built in rings like a larue spr mount. It does only tighten on the left, which I thought was probably causing the problem but I dont think that I am overtightening it because I am only hand tightening it, I tried to leave it a little loose but with no success.

As per the gunsmithing, this will probably end up being what I do, but I'm broke so the temptation is strong to try and remove the handguard and check it myself. I did not cross thread the barrel nut, I know that for sure. What does it mean to have the nut out of alignment?

Also, I am unsure how to find a good gunsmith. Gander mountain has one, but they charge a hefty sum, as I had looked at them doing it before. I have put a lot of money and time into this build and don't want to pass it off to just anyone.

Thanks again.

[Gene Econ]

Originally Posted by fng13

I am using the burris P.E.P.R. Mount, it is a single mount with 2 built in rings like a larue spr mount. It does only tighten on the left, which I thought was probably causing the problem but I dont think that I am overtightening it because I am only hand tightening it, I tried to leave it a little loose but with no success.

As per the gunsmithing, this will probably end up being what I do, but I'm broke so the temptation is strong to try and remove the handguard and check it myself. I did not cross thread the barrel nut, I know that for sure. What does it mean to have the nut out of alignment?

Also, I am unsure how to find a good gunsmith. Gander mountain has one, but they charge a hefty sum, as I had looked at them doing it before. I have put a lot of money and time into this build and don't want to pass it off to just anyone.

Thanks again.

FNG:

One thing I forgot to ask.

Did you zero the upper using any iron sights? If you did zero it with a set of irons and had no problems with windage, something is wrong with the scope mounts or optic.

If you have a set of irons, slap them on and try to zero. If the same thing happens, the barrel was put on crooked.

You didn't have problems posting to this forum. What makes you think you will have any problems finding someone who is competent at making AR-15's? Come on guy...

Gene

[TF Kilo]

If it's that short of a barrel, you could always run a cleaning rod through it and just let it sit in the barrel far enough out that you can see if it's actually off kilter. I'd recommend having a gunsmith check it out as well.

[Peregrino]

PM sent.

[Sabre2G]

If your really trying to go the way of the gunsmith for the time being you could try a laser bore alignment and go from there. If it's still that bad I agree with everyone else either send the sight and mounts back for a new set or go to a gunsmith. Just my $.02

[fng13]

Originally Posted by Gene Econ

FNG:

One thing I forgot to ask.

Did you zero the upper using any iron sights? If you did zero it with a set of irons and had no problems with windage, something is wrong with the scope mounts or optic.

If you have a set of irons, slap them on and try to zero. If the same thing happens, the barrel was put on crooked.

You didn't have problems posting to this forum. What makes you think you will have any problems finding someone who is competent at making AR-15's? Come on guy...

Gene

I had gotten magpul mbus sights and did sight them in at the same time as the scope. I did have to adjust the windage to the right. However I did not use all of the adjustment. There is 15-20 "clicks" left on the right adjustment, I dont know what that transfers to, but looking at the knob it seems to be 1/4 turns. It is easy to see that the sight is not centered by looking at it in position to the base of the sight. Would this be indicative of poor barrel alignment?

I am still confused how I would have got the barrel out of alignment. It looks strait and was never taken out of the notch in the upper. This upper is from a stag arms model 1, with a 16in barrel. I had an eotech xps2 on there before I put the new rail system on and had no problems zeroing that. I understand though that an electronic optic probably has a greater level of adjustment.


I don't have a camera other than my cell phone but I'll try and borrow one so that I can post pics.

As per finding a gun smith, I was thinking of finding one locally. I have never taken anything to one before, so I didn't know what to look for. This has been corrected.

Thanks

[longrange1947]

Stick a cleaning rod down the barrel so that 12 to 18 inches or more is sticking out of the the muzzle, That will show the displacement. Understand this, 60 moa equal ONE degree. Without a good, and I mean good, reference it is hard to see less than one degree of displacement in barrel. Your scope probably has about 40 moa adjustment. That means about 2/3s of a degree.

You stated that you had your weapon on its side as you took off the old barrel nut. That means that the barrel was unsupported, whether it was take out of the notch or not, the barrel probably sagged just a bit. That is all it takes, that just a bit.

My two cents.

[NousDefionsDoc]

Originally Posted by longrange1947

My two cents.

ROTFLMAO! Oh that I had that drawing interest from when I first met this one...

[fng13]

Originally Posted by longrange1947

Stick a cleaning rod down the barrel so that 12 to 18 inches or more is sticking out of the the muzzle, That will show the displacement. Understand this, 60 moa equal ONE degree. Without a good, and I mean good, reference it is hard to see less than one degree of displacement in barrel. Your scope probably has about 40 moa adjustment. That means about 2/3s of a degree.

You stated that you had your weapon on its side as you took off the old barrel nut. That means that the barrel was unsupported, whether it was take out of the notch or not, the barrel probably sagged just a bit. That is all it takes, that just a bit.

My two cents.

Then I'm sure thats what happened. I may try to fix this myself. Will the barrel maintain alignment if i simply finger tighten the barrel nut on? I am using "Blox Worx" blocks, that hold the upper receiver pinched inbetween them so that the receiver doesn't get bent. So I don't want to torque on the barrel until it is correctly in the vice. Maybe tighten it a little then put it in the vice? How can I ensure proper barrel alignment? Without a special tool?

Thanks,
Fng