Problem with ar10

Bradu

Full Member
Full Member
Minuteman
Aug 24, 2011
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I was shooting my Gap built Armalite Ar10 yesterday and I went to empty a live round out of the chamber the bullet pulled out of the brass. I had to get a cleaning rod and punch it out of the barrel. It was a factory FGMM 168 grain and it had no signs it was touching the lands so what would have caused it? I'm just trying to figure out what happened, I will try to find the bullet in the back of the Jeep and post a pic of it. I have fired about 150 rounds through it without a single issue until yesterday.
 
Re: Problem with ar10

Check the brass of the extracted round to see if the primer ignited. If the primer primer was struck, AND there are obvious signs of ignition inside the brass i.e.: fouling inside the brass, then you had a squib round, i.e. - no powder in the brass and primer pushed the bullet an inch down the barrel.

If you pulled the empty shell out, and the powder was all over the inside of the chamber, the the bullet kept going forward when the bolt stopped as you were chambering the round. This is unusual, but eh, it could happen, likely that under that loose of neck tension would have allowed the bullet to fall out a long before you loaded it.

It unlikely that the bullet was seated too long and got stuck in the lands. A bullet that long would not fit in the magazine in the first place. You would have had to chamber load it. AND, there is not enough tension in the lands to hold a bullet while you pull the bolt back. This scenario is not probable for a few other reasons.

Any of these is very unusual with factory rounds especially Federal GMM. You need to examine the brass and bullet very carefully and diagnose what happened.
It is generally not good to send a bullet down the barrel with one already stuck there. Im not totally sure what would happen, but I am certain you would not like the result.
 
Re: Problem with ar10

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body">Two things. It is either forced into the lands and sticking or there was not enough neck tension to hold the bullet in the case. Either way you need to get it figured out before you shoot it again. </div></div>

Agreed, I have had that happen but it was always due to the neck tension not being tight enough. I have never had that happen in thousands of rounds of FGMM but anyhting can happen even with those rounds given howmany they produce. I also do not think the OAL was long enough to stick in the rifling as the found would most probably not fit in the magazine.
 
Re: Problem with ar10

Thanks guys, I can't find the bullet to take a pic but it didn't look like it touched the lands and powder went everywhere in the chamber when I pulled the round out. I will try some more ammo out of that box to see if it happens again.
 
Re: Problem with ar10

Is this the first time? Our chamber is pretty tight and does take some breaking in. If the ammo you are shooting has 168 grain Sierra pills, then that may be your problem. 80% of the bullet pulling issue has been with the Sierra 168gr in Federal and even Black Hills ammo. Also if there is carbon build up at the "lead" of the chamber, it may cause this issue. Show some pictures up and we can get this taken care of. You can also e-mail them and I can help you out.

[email protected]
 
Re: Problem with ar10

It was the first and only time it's ever happened. I have the primed brass but the guy I went shooting with has it so I will try to get the bullet from him this week and get you some pics. I take it you have seen the problem before with the 168 sierra's? If so, I will switch to 175's.
 
Re: Problem with ar10

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DUSTIN@GAP</div><div class="ubbcode-body">Is this the first time? Our chamber is pretty tight and does take some breaking in. If the ammo you are shooting has 168 grain Sierra pills, then that may be your problem. 80% of the bullet pulling issue has been with the Sierra 168gr in Federal and even Black Hills ammo. Also if there is carbon build up at the "lead" of the chamber, it may cause this issue. Show some pictures up and we can get this taken care of. You can also e-mail them and I can help you out.

[email protected]</div></div>
Wow is that customer service or what. The factory guys giving you a response in a forum on the same day. Maybe I need one of those AR-10's myself before they outlaw the Bullet Button out here in Kalifornia
 
Re: Problem with ar10

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DUSTIN@GAP</div><div class="ubbcode-body">Is this the first time? Our chamber is pretty tight and does take some breaking in. If the ammo you are shooting has 168 grain Sierra pills, then that may be your problem. 80% of the bullet pulling issue has been with the Sierra 168gr in Federal and even Black Hills ammo. Also if there is carbon build up at the "lead" of the chamber, it may cause this issue. Show some pictures up and we can get this taken care of. You can also e-mail them and I can help you out.

[email protected]</div></div>
Wow is that customer service or what. The factory guys giving you a response in a forum on the same day. Maybe I need one of those AR-10's myself before they outlaw the Bullet Button out here in Kalifornia </div></div>

That is good customer care. Its wonderful that a lot of things get directly addressed here. How you break in a chamber Dustin?
 
Re: Problem with ar10

I have attached our break-in instructions. They are pretty straight forward. As with any Semi-Auto platform, the more you shoot them the smoother they run. Remember you have a bunch of moving parts that have very little tolerance. I would personally say that breaking in a semi auto is more imperative than a bolt gun for functionality. Here ya go.

The G.A. Precision Break In Procedure For break-in, the barrel should be cleaned after every shot for the first 10-12 rounds or until copper fouling stops. Our procedure, outlined below consists of removing the carbon fouling followed by the copper fouling.

Step 1 Carbon Fouling: Push 2 saturated cotton patches through the barrel (Bore Tech C4 Carbon Remover or Eliminator Bore Cleaner). This will remove the loose powder fouling and wet the inside of the barrel with solvent. Next, wet a nylon brush with solvent and stroke the inside of the barrel 5-10 times. This is followed by another wet patch and then 2 dry patches.

Step 2 Copper Fouling: Now, push 2 saturated cotton patches through the barrel (Bore Tech Cu+2 Copper Remover or Eliminator Bore Cleaner,). Next, wet a nylon brush with solvent and stroke the inside of the barrel 5-10 times. Let the chemical soak for 3-5 minutes. This is followed by another wet patch and then 2 dry patches. Repeat steps if necessary.

REPEAT: Steps 1 & 2 after each shot for the first 10-12 rounds.

The copper fouling will be heavy for a few rounds and then taper off quickly in just one or two shots. Once it has stopped or diminished significantly (normally 10-12 rounds) it is time to start shooting 5 shot groups, cleaning after each one. After 25-30 rounds, clean at a normal interval of 10-25 rounds. Your barrel is now broken-in.

IMPORTANT: Be sure to dry out the chamber after cleaning to remove solvent, a pistol rod with a 45 cal nylon brush works well using a patch over it. Failure to keep the chamber clean and dry will raise pressure to extreme levels.
 
Re: Problem with ar10

I still haven't got my hands on the bullet yet so I can get pictures but I'm trying because I really want to know what's going on for sure. I want to say that I am pleased to see Dustin active in this thread and I want people to know that I am in no way unsatisfied with the rifle. It is one hell of a shooter and is one of my favorite rifles that I own. I have made some people believers in semi autos after they seen this rifle and my RWS ar shoot.
 
Re: Problem with ar10

Id think the bullet was forced into the lands, or perhaps neck tension was insufficient... More likely the first cause though, as I almost broke a bullet puller once trying to pull a 168 FGMM round.
 
Re: Problem with ar10

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Here are some pics, I tried to rotate the bullet 180* to show both sides. If there are any other pics needed let me know and I will try my best to get them. I'm by no means a photographer so these are as close as I could get without them getting blurry.