AG-42b Out of battery detonation

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Eaglelord17

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Hi all,

I felt I would share with you all my most recent experience at my latest range trip.

Yesterday I was shooting my new to me AG-42b and I experienced a out of battery detonation. The rifle doubled (or tripled not sure how many rounds were fired) in full auto for a second and one of the rounds it fired was about 1/4 to 1/2 inch out of battery. The rifle then dumped the gasses down the magazine well (like they are meant to in these type of situations) and blew off the bottom of the magazine and the magazine spring (follower was held in place by the pin in the magazine). No one was hurt as the rifle functioned as it was supposed to (well in regards to a out of battery failure), and the rifle was also surprisingly completely fine (no damage done whatsoever) which speaks volumes about the quality of the firearm. After taking a look at it (a qualified gunsmith was also on the range at the same time and he took a quick look as well) and verifying nothing was wrong I continued shooting except as single rounds (the rounds were getting stuck in the chamber anyways we figure due to higher pressure rounds then the original design which was the M94 6.5 Swedish).

The rifle is pretty accurate though, and even though it did full auto for a second all the rounds were on the paper.
Here is some photos (the rifle is pretty much like new) of the rifle and the case that was fired out of battery. Remember to wear eye protection as accidents do happen and always verify the safety of a rifle before you shoot it.





 
Yikes! Glad you are okay and still have all the same parts you started with.

If it were me, don't think I could have continued shooting the rifle that day until I took it home and went over the rifle with a microscope!
 
Continuing to shoot a rifle obviously in need of care would get you kicked off my range. 'Stuck in the chamber' is a failure to extract. One of the indicators of excess headspace. As well as excess pressure. What ammo?
 
Firing off a double feed is very uncommon. At least in most new firearms I've had, semi auto. I've never been able to drop pin while having a double feed. They do happen time to time and can go unnoticed. Glad your ok, I would have got it all cleared up, checked it out and continued shooting very carefully... Making sure bolts down, its extracting properly ect. ect. to see if I could make it happen again (the double feed, not the boom part lol). What did the gunsmith have to say ?
 
In an AG42B, the most common cause of failure to extract is ammunition which produces too high a residual pressure in the case when the bullet passes the gas port, and the action attempts to open. It is not that the cartridge is over pressure, the problem is that the burning rate is inappropriate.
This is very common if the ammunition is inappropriate for the rifle.
Usually the extractor rips through the rim as the breech opens, leaving the case behind. Lock the bolt open, point the rifle up, and the case is likely to fall out.

This is nothing to do with the case failure that you experienced.
If a round fires when partially chambered, it tends to separate, blowing the casehead off, with a clearly defined ring showing where the cartridge was when ignition occurred.
In your photos, the case is ripped open, and doesn't seem to have been in the chamber at all.
What happened to the bullet? Where did it go?
 
Just Federal and S&B 6.5x55 (detonation happened with the Federal). The rifle has proper headspace, all the other brass proves that. Apparently the Swedish used to oil the M41 ammo (but not the M94) as it would aid in ejecting the M41 ammo as it ran at a higher pressure.
 
If you look at the case, it neck sized on the very tip of the case (the gunsmith pointed this out). All the bullets from that group ended up down range on the paper so the bullet travelled where it was supposed to.
 
I wonder if the breech was able to open while residual pressure was high enough to split the case when it was almost completely extracted.
Never heard of anything like this before.
I am aware of the oil the M41 cartridges solution to address the failure to extract problem, and have seen it done.

It is worth noting that when the Swedes disposed of their obsolete firearms, the M94 carbine went first, followed by the AG42Bs, then the M38s, with the M96s last. They hung on to these because they were the best shooters. The AG42Bs were never trouble free.
 
It was very weird. Not something I would like to have happen again (and for that reason I am going to be keeping the rifle as a collector piece at least until I start making some M94 grade ammo). I figure the firing pin spring might be a bit too weak to hold back the firing pin enough, combined with softer civilian spec primers might have cause a strike before it was fully locked in battery (which would also explain why it double tapped).

In any case I will go back to shooting my bolt-actions primarily as I don't really have to deal with these types of issues.
 
I suppose that an AG42B could slamfire, particularly with soft primers. Was the doubling with the Federal ammunition or with the S&B?
 
The rifle has a spring on the firing pin to try to reduce the risk of a slam fire. On my rifle, chambered rounds alwys have a clean indent from the firing pin, when the round chambered.

This, coupled with a sensitive (Federal) primer could cause an out of battery. My rifle came with a small kit that included a spare firing pin spring. I installed it, doubling up on the protection. This makes me feel a bit safer.

If you look at your AG42b bolt, you will see that the firing pin spring is a garden variety size, so if you look around your junk bin, you might find another one to add, or a stiffer one to replace the original.
 
Some gas operated semi automatic rifles have to have the gas system balanced for the ammunition.

Different ammunition produces different amounts of gas and pressure.

For the Canadian FN C1, there was a drill that was taught on how to use the gas regulator to balance the amount of gas going to the piston.

The Egyptian Hakim and the Rashid have gas adjustment ports.

Google "AG 42b gas system adjustment"

And read the sticky = http://www.canadiangunnutz.com/forum/showthread.php/777762-The-AG42-rifle-egyptian-Hakim-amp-Rasheed
 
Last edited:
sail32 said:
Some gas operated semi automatic rifles have to have the gas system balanced for the ammunition.

Different ammunition produces different amounts of gas and pressure.

For the Canadian FN C1, there was a drill that was taught on how to use the gas regulator to balance the amount of gas going to the piston.

The Egyptian Hakim and the AG 42b have gas adjustment ports.

Google "AG 42b gas system adjustment"

And read the sticky = http://www.canadiangunnutz.com/forum/showthread.php/777762-The-AG42-rifle-egyptian-Hakim-amp-Rasheed
Click to expand...

Unfortunately the AG-42b doesn't have a gas adjustment system (very much like a AR-15 in that regard), that was added for the Hakim due to the sand and major variations between different batches of 8mm Mauser.

Also I am not sure if this matters but the other piece of brass from the burst had the primer completely blown out of the socket.
 
Uncontrollable slam fires are not Full Auto. One is a malfunction, the other is a design function. Please use proper terminology especially on a public site like CGN so not to muddy the waters.
 
If the cases were sticking you may also need to replace the extractor and spring. I used to own one and at first I couldn't get it to fire five rounds in a row. Replaced the extractor and it cycled like a dream.
 
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