AR-10 First shot high???

[magyarbetyar]

I am having a problem with my AR-10 and was wondering if anyone else has had or seen this problem.

First the rifle is and Armalite upper with 24" barrel, Noveske lower with JP rifles trigger group and Nightforce 3.5-15x56 optic. I am handloading once fired winchester brass with 44gr of varget pushing a 150 gr amax bullet lit off by winchester pimers. I am running no crimp on the brass just neck tension. I have take random rounds and cycled them through the action several times to see if there is any change in OAL and I have not had any issues.

Now the problem. I load for 5 shot strings and the first round is always high 2-3 inches and the subsequent shots are on target and in a nice group. The only thing I can think of is the way I am loading the first round. The bolt is locked back, I insert the magazine and use the bolt release to load the first round. Can using the bolt release vs pulling the bolt all the way back via the charging handle to load make that much of a difference?

 

[4Rail_Gunner]

Re: AR-10 First shot high???

Load 5 shots.
drop the bolt on the first bullet.
pull it out.
empty the mag, put the first bullet in the mag then load the rest.
Then see if your first and fifth shot are both high.

On a serious note though.
Is it changing your headspacing?
either changing it on the first shot or possibly the first shot headspace is normal and your other rounds are getting their headspace changed.

?

 

[SmokeRolls]

Re: AR-10 First shot high???

Or is it just a substantial difference between the first cold bore shot and barrel warming up? Either way thats a pretty big jump.........

To rule out cold bore difference, you can wait until barrel temp goes back to ambient (Let her sit for a while and then try another cold bore and check your grouping)to rule that out.

I'm not saying I'm right but I am currious either way..........Just an idea........SmokeRolls

 

[magyarbetyar]

Re: AR-10 First shot high???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 4Rail_Gunner</div><div class="ubbcode-body">Load 5 shots.
drop the bolt on the first bullet.
pull it out.
empty the mag, put the first bullet in the mag then load the rest.
Then see if your first and fifth shot are both high.

On a serious note though.
Is it changing your headspacing?
either changing it on the first shot or possibly the first shot headspace is normal and your other rounds are getting their headspace changed.

? </div></div>

This is not a bad idea. I will give it a try. Also the barrel temp actually luke warm not really "cold" bore. I fire a couple of foulers and get right to work. I let the barrel cool between the five shot strings a bit though but not "cold".

 

[jrob300]

Re: AR-10 First shot high???

Try single feeding to give yourself a data point.

Also check for bullet setback in rounds 2-5. Will change chamber pressure.

John

 

[4Rail_Gunner]

Re: AR-10 First shot high???

What does the gun do on an actual cold bore?

And you said that you shoot a couple of foulers, so does that mean that you clean way to much and clean it after every trip to the range?


Also,
does this happen every 5 shot group you shoot? or just after the foulers and then a fresh 5 shot mag?

 

[gunsnjeeps]

Re: AR-10 First shot high???

Does this happen on factory ammo or just hand loads? Try loading a magazine on a closed bolt and loading with the charging handle rather than inserting the mag with the bolt open. I'm guessing that it happens from more than one magazine, but try a different mag. I'd also look at lube and cleaning just to make sure.

Could there be a position problem on the first round that you are correcting after recoil? Load a mag shoot two rounds then set the rifle down and reposition then shoot the next three.

 

[filefish]

Re: AR-10 First shot high???

I am assuming that you are shooting at 100 yards, and 2-3 inches is quite a bit at that distance...

if your theory (as it sounds to me) is that your bolt is not going fully in to battery when the bolt is dropped from the release, then I probably would not shoot the gun until I had it checked by a <span style="text-decoration: underline">qualified</span> AR10 gunsmith... this could be bad. i might also call Armalite and discuss your problem, they are very helpful (800) 336-0184

 

[filefish]

Re: AR-10 First shot high???

another thing to check

load your mag
drop your bolt
fire 1 round
pull your charging handle and check the OLL on the live round that just flopped on the floor, check other case dimensions as well

 

[gnfiter3]

Re: AR-10 First shot high???

No problem of this nature with my straight stock Armalite. What is the position relative to POA and POI of the fouling shots. Single feed as suggested and see where you are?

 

[esorensen]

Re: AR-10 First shot high???

Some may disagree, but I had a similar issue with the AR-10T. It would put #1 about and inch high. I insert the first round INTO the chamber, and drop the bolt on it, and the rest feed from the mag. Problem solved for me.

 

[gnfiter3]

Re: AR-10 First shot high???

Yeah, but you'd think that shouldn't be required???

 

[Natty Bumpo]

Re: AR-10 First shot high???

I've noticed the a similar issue with my AR-15. First round from the magazine doesn't quite go where the others go. Load 10 rounds and shoot 2 5-shot groups. Is the first shot in the 2nd group a flier? Also try loading your magazine one at a time for 5 shots. Do those 5 all group together?

 

[iShot]

Re: AR-10 First shot high???

I'm as green as they come to shooting and I'm in the market for an AR-10 or 15. I'm looking strictly for long range accuracy and won't spend more than 3000. I've been looking at a GA Precision AR-10 but was wondering if it is worth the high cost. Any information will be helpfull.

 

[DaveV]

Re: AR-10 First shot high???

There's a difference between cold bore and clean cold bore. Most BR guys can tell you where their first CCB shot will go. Since you said you shoot foulers, this rules that out. Did I understand you as saying you shoot foulers then, the first shot out of a 5 shot string is the problem child?

 

[magyarbetyar]

Re: AR-10 First shot high???

There is some great advise here I will try to narrow down my problem. To answer some of the questions: The flier in question is always the first round manually loaded into the weapon. The subseqent rounds that the weapon feeds itself are were they are supposed to be. So if I load 5 the first is high the 4 are good. If I load 20 the first is high the 19 are good.

And the way I am loading the weapon is I will lock back the bolt insert loaded magazine and drop the bolt using the bolt release.

As for the foulers I did clean my weapon and that is why I shot the foulers.

As for the cleaning of the weapon I do clean it after every range session unless I know I will be going again very soon. However being as my schedule changes and my trips to the range are determined in the last minute I like to keep it clean.

 

[smokebomb]

Re: AR-10 First shot high???

I am having a similar issue w/ my ar15. The first round manually loaded will impact 2-3" seperate from subsequent shots. I will try manually feeding a 5 shot group.
However, my ar15 does this w/ factory and reloaded ammo... It has been exceptionally frustrating...

 

[DH]

Re: AR-10 First shot high???

I have had this problem with precision AR-15s to some degree over the years. Usually the first rd flier adds about 1/4-1/2" to the groups size. Just the other day, I think on AR15, someone was asking about accurizing a M1A. Most over there said they are nice but a pain to accurise and keep that way. No major revelation, until a guy was talking about mag spring tension and how that can affect the 1st rd flier. Wonder if that has anything to do with ARs problem. I am not to worried about the slight amount my first rd goes off but 2-3" is alot.

 

[DustyJacket]

Re: AR-10 First shot high???

Try this:

Do your normal 'manual load' but don't shoot it. Cycle the action and save the round.

Fire a few rounds normally, and eject the next automatically chambered round without firing it.

Compare the 2 rounds for setback, gouges, etc.

If they are identical then you'll have to look at the rifle for a cause.

Do another experiment and save the empty shell from your 'manually loaded' round and one of you automatically loaded rounds, and compare them for bulges at the base, or deformed necks, or whatever.

 

[colt933]

Re: AR-10 First shot high???

I had an AR10T Armalite 24" barrel that had a similar issue, but not identical.

The rifle would shoot two different groups one about 3-4" above the other one. There didn't seem to be any correlation with the shot sequence and which group the shot went into. If you took 5 shots, 2-3 would be in one group and the other 2-3 would be in the other group. If you shot 20 shots, then they would be evenly dispersed between the two different groups. Each group was about 1MOA, but the total group size between the two groups was about 5MOA.

The really crazy thing is that my friend had one of the first AR10T rifles back in the early nineties. He pre-ordered before they were actually released. I think these early rifles had Mike Rock barrels. Anyway, his did exactly the same thing as mine did. Two different groups in the same shot string.

I tried several types of factory ammo and my handloads and swapped optics and rings a couple of times. Eventually I sent it back to Armalite. They claimed that they re-crowned, polished the chamber, and re-torqued the barrel. It shot 1MOA when it came back. But I sold it and got a Noveske barrel and all is well now!

 

[The Mechanic]

Re: AR-10 First shot high???

First thing to do is hand it off to someone else and let them fire it and see if they get the exact same results. Do not tell them your problem with the rifle. May just be you and your cold body first shot

 

[DustyJacket]

Re: AR-10 First shot high???

So, how did this work out?

 

[magyarbetyar]

Re: AR-10 First shot high???

I know this is old, but I have since figured out the problem with my particular rifle. The other day I was cleaning it and noticed an imprint of the gas block on the forearm end. Now it was not really and "imprint" more like rub marks. It is only logical to assume that is what is causing my consistency issuse with this rifle.

I have ordered and JP rifles 15" forearm and their lo-pro adjustable gas block. Once it arrives and I am able to put some rounds down range I will report back.

 

[magyarbetyar]

Re: AR-10 First shot high???

Range Report.

Still a problem with consistency. Have achieved sub MOA @ 100yds, however not on a consistent basis. Solution contacted Armalite and they told me to send it in. Prognosis: incorrect chamber dimensions. Barrel, gas block, charging handle and gas tube all replace under warranty. Waiting arrival of upper in mail for a test run at range.

I spoke with one of the lead armorers and after repairs he personally put some 175gr Black Hills through it and told me it was a one hole pattern.

Can't wait to put rounds down range.

Will report back after.