A little help with my AR please

[jnyork]

Thought I would shoot a string of offhand this morning, all went well until the 17th shot, which stuck a cartridge case in the chamber. Report was somewhat louder, bullet exited the barrel, no gas or debris in my face or obvious damage to the gun. Bolt will come back about 1/8 inch or so. I used a rod and hit it a couple of pretty good smacks, no joy, also bumped the charging handle pretty well, same thing. Now what, any tricks anyone knows? Thought I might fill the bore with Kroil for a while and see if that loosens things up.

[jhrosier]

I would take the upper off the gun.
you have better access to the bolt through the bottom.
Probably enough room to sneak a piece of brass or aluminum bar stock in to tap the bolt carrier to the rear.

good luck.

Jack

[jnyork]

Thanks, Jack, a guy on another forum instructed me on how to bump the butt of the rifle smartly on a hard surface. Worked great.


Rifle is a Colt HBAR Match Target, A2. Have had it for over 20 years, first malfunction and not the fault of the rifle.

I did the "whack the butt on the floor" routine, only took about 3 whacks and it came on out. Case was stuck in the boltface, primer was blown and missing , face of casehead was badly buggered, head of case very noticeably expanded for a distance of 50-60 thousanths in front of the rim.

I am at a loss to explain this very high pressure. Load was 19 grains of AA2200 and 77 grain bullet, Remington Small Rifle primer. Impossible to double charge this load. I always dump powder in a full tray full of cases, then carefully check each one individually with a flashlight. Other cases show no signs of pressure whatsoever. Real mystery to me.

Anyway, thanks everyone , Best Regards to all.

[wm]

Could it have been a bad crimp and the bullet worked its way back into the case? I've heard of this happening to others.

[jnyork]

Could it have been a bad crimp and the bullet worked its way back into the case? I've heard of this happening to others.

I load singly in offhand, single shot adaptor magazine.

[7.62 Precision]

1. Could it have been that a bit of wrong powder got mixed in? This happens quite often.

2. Could the rifle have fired out of battery? It is an old Colt, so it will have the cut-down semi-auto bolt carrier that can allow an OOB discharge. The rear send of the cartridge being bulged could indicate this.

3. Sizing is very important on 5.56 cartridges. From what I understand, improperly-sized cartridges can lead to overpressure issues. Could this be an issue?

[Streetstar]

I have had odd things occur when the gas key works itself loose (staked or not)

[jnyork]

[quote="7.62 Precision"]1.
2. Could the rifle have fired out of battery? It is an old Colt, so it will have the cut-down semi-auto bolt carrier that can allow an OOB discharge. The rear send of the cartridge being bulged could indicate this.


Are you saying the rifle will fire with the trigger even if it is not completely locked up? The round did not discharge when the bolt went closed, it discharged when I fired the gun with the trigger.

[shooter]

Check the specs on the upper before shooting the gun again. Had this very thing happen while I was shooting a friend's AR. Didn't blow up the gun, but I felt the blowback on my face, and it blew out the bottom of the magazine. After we got the case cleared, all looked kosher with the gun, but we decided not to shoot it anymore until we checked it out. Sure enough, the pressure had bulged the upper ever so slightly, making it unsafe to fire. We never knew what the cause of the malfunction was, but my buddy called the manufacturer, DPMS, and they sent him a new upper free of charge after inspecting the old one.

[7.62 Precision]

Yes.

When Colt first started making semi-auto rifles, they went overboard on changing things between the semi-auto and full auto versions. All of this was supposedly to keep people from making the rifles full auto, but I think it was more designed to keep people from being able to use any surplus parts, forcing them to buy from Colt, when Colt thought they would be able to be the only player.

Colt changed the hammer so it would not only not work with the full-auto fire control parts, but leo so it would not work right with a full auto bolt carrier. They used larger pins so surplus uppers could not be used. They changed the bolt carrier, etc.

In removing material from the bolt carrier, they also made it possible for the rifle to fire out of battery. This is also the case with some pistol caliber blow-back bolt carriers, and some other companies also followed Colt's lead in changing the bolt carriers. Most semi-auto bolt carriers are no longer built that way. Colt eventually dropped a lot of this stuff when they realized it was not to their advantage.

I use full-auto (M16) bolt carriers since the ATFE ruled that they do not make an AR-15 a machine gun.


Top is earlier Colt, center is semi-auto, and bottom is full auto.

If yours looks like the top, and you change it to a shrouded bolt carrier (like the bottom two), you also must change the firing pin.

An enshrouded bolt carrier will likely work just fine usually. If you have problems with it, it is going to be related to other problems as well. Still, I stick with the shrouded carriers, M16 carriers preferably.

[7.62 Precision]

Check the specs on the upper before shooting the gun again. Had this very thing happen while I was shooting a friend's AR. Didn't blow up the gun, but I felt the blowback on my face, and it blew out the bottom of the magazine. After we got the case cleared, all looked kosher with the gun, but we decided not to shoot it anymore until we checked it out. Sure enough, the pressure had bulged the upper ever so slightly, making it unsafe to fire. We never knew what the cause of the malfunction was, but my buddy called the manufacturer, DPMS, and they sent him a new upper free of charge after inspecting the old one.

His case did not rupture, so his upper should be OK.

[Mich Hunter]

Thought I would shoot a string of offhand this morning, all went well until the 17th shot, which stuck a cartridge case in the chamber. Report was somewhat louder, bullet exited the barrel, no gas or debris in my face or obvious damage to the gun. Bolt will come back about 1/8 inch or so. I used a rod and hit it a couple of pretty good smacks, no joy, also bumped the charging handle pretty well, same thing. Now what, any tricks anyone knows? Thought I might fill the bore with Kroil for a while and see if that loosens things up.

jnyork,

I have seen this issue quite a bit when the AF switched over to frang ammo in the 5.56mm for training. Federal was known to get through an occasional "hot round" which would do exactly what you just described and more. It can cause the extractor to bend outwards causing the entire carrier assembly to get stuck in the forward position. This will also cause the bolt to not unlock properly. Consider yourself a little lucky as I have seen M4's & M16A2's do this to where the magazine will completely blow out of the bottom of the rifle and slit in half due to pressures. I have also seen where the bolt carrier itself slit in half and the entire bottom and upper receiver bulged. This was with standard ball ammo. I think I still have the pictures and will try and post later.

What I have had to do in the past was separate the upper and lower to try and get a flash light up into the chamber area. Once you do this, pay particular attention to the extractor. Check to see if it is still somewhat flush with the bolt. I am 95% sure this is your issue. If in fact it is, you can handle in a couple ways. Take a cleaning rod down the bore and whack it with a BFR. If not, your barrel will probably need to be loosened in order to get the bolt out. Lastly, if you can get a punch to the extractor try putting pressure on it inward to see if the bolt will unlock.

Once you get everything apart, I would make sure the upper and lower are still in spec and the barrel is not bulged. 99% of the time, the barrel will not be damaged but pay attention to the upper receiver for cracks.

[7.62 Precision]

. . . when the AF switched over to frang ammo in the 5.56mm . . .

Had a friend who was an AF combat arms instructor. They were replacing bolts like crazy when they were shooting the frangible stuff.

[Mich Hunter]

. . . when the AF switched over to frang ammo in the 5.56mm . . .

Had a friend who was an AF combat arms instructor. They were replacing bolts like crazy when they were shooting the frangible stuff.

I have spent the last 15 years on the range as a AF Combat Arms guy Frangible was terrible and we saw more damage with frang than we every saw with ball. It was also extremely dirty and had some severe health side effects. I felt like I worked in a coal mine after shooting that stuff.

[Griff]

Also, check the case... resize it, put in a used primer if it'll hold one, check how many cc's of water that case holds compared to another of that same lot.

And remember, bullets can gget pushed back in the case when cycling thru the action. Crimp mighta been just lax enough.

[MrMurphy]

We didn't care to use the frangible stuff either, so don't feel lonely....

[jnyork]

Also, check the case... resize it, put in a used primer if it'll hold one, check how many cc's of water that case holds compared to another of that same lot.

And remember, bullets can gget pushed back in the case when cycling thru the action. Crimp mighta been just lax enough.

Thanks, Griff, case is WAY beyond that. I was single-loading, so I don't think it was the crimp.

[Rusty]

Just a question because I don't know the answer in relation to single feeding.

With a Mauser bolt action we are always taught to only feed from the magazine so the extractor will slip over the rim of the cartridge. With a Glock and other semi auto pistols I am told the correct method is to load a magazine into the gun rack the slide, then remove the magazine and top off the magazine. Never drop a loaded round into the chamber and allow the slide to go home.

That said, should an AR be loaded the same way? I am thinking so, but not sure it maters.

[jnyork]

Just a question because I don't know the answer in relation to single feeding.

With a Mauser bolt action we are always taught to only feed from the magazine so the extractor will slip over the rim of the cartridge. With a Glock and other semi auto pistols I am told the correct method is to load a magazine into the gun rack the slide, then remove the magazine and top off the magazine. Never drop a loaded round into the chamber and allow the slide to go home.

That said, should an AR be loaded the same way? I am thinking so, but not sure it maters.

With the AR, you get a single-shot follower from Sinclair and install it in a mag. Then, all you have to do is place the round on the follower and close the bolt. You don't drop a round in the chamber, the round feeds from the follower.

[AJMD429]

Check the specs on the upper before shooting the gun again. Had this very thing happen while I was shooting a friend's AR. Didn't blow up the gun, but I felt the blowback on my face, and it blew out the bottom of the magazine. After we got the case cleared, all looked kosher with the gun, but we decided not to shoot it anymore until we checked it out. Sure enough, the pressure had bulged the upper ever so slightly, making it unsafe to fire. We never knew what the cause of the malfunction was, but my buddy called the manufacturer, DPMS, and they sent him a new upper free of charge after inspecting the old one.

Thanks for the info - this is very interesting.

Too many semiautos can fire without being fully locked-up...

[AJMD429]

2. Could the rifle have fired out of battery? It is an old Colt, so it will have the cut-down semi-auto bolt carrier that can allow an OOB discharge. The rear send of the cartridge being bulged could indicate this.

That would be my impression, just off-hand...

[7.62 Precision]

Just a question because I don't know the answer in relation to single feeding.

With a Mauser bolt action we are always taught to only feed from the magazine so the extractor will slip over the rim of the cartridge. With a Glock and other semi auto pistols I am told the correct method is to load a magazine into the gun rack the slide, then remove the magazine and top off the magazine. Never drop a loaded round into the chamber and allow the slide to go home.

That said, should an AR be loaded the same way? I am thinking so, but not sure it maters.

The AR is different as far as the bolt/extractor design goes. You can drop a round in the chamber, and drop the bolt on it, and it will not damage the extractor (like a Remington 700 or post-64 Winchester 70 with push feed extractor.

Almost every auto pistol should be loaded from the magazine to avoid damage, as well as controlled-round feed rifles like your Mauser, pre-64 (or later model M70 with CRF).

That is the simple answer. However, there is a reason it may be wise to load an AR from a magazine; the friction of loading from a magazine slows the bolt and may prevent slam fires with certain loads that may have high or soft primers. Competitions shooters using the previously mentioned single-shot followers have had slam fires. Was it because of extra bolt velocity? I don' know, but many feel it is, so a lot of people recommend loading from a magazine. There are also single shot followers designed to slow the bolt as well, I hear.