need advice: Maadi piercing primers

[5.0guy7]

I recently purchased my first AK 47 a Egyptian Maadi from a guy at a local show. I took it to the range and it fired twice and smoke rolled out of the back of the receiver and on the third shot it only clicked and dented the primer. Upon inspection of the two discharged cartridges both had their primers punctured. I disassembled the bolt and found debris from the primers in the firing pin channel. I ordered a replacement firing pin, installed it and went back to the range with a few different brands of ammo. This time I got about 10 cycles and same thing. I removed the firing pin and found the same debris, removed them and tried with another brand of ammo, same thing.
The guy at the show is long gone, so I need to find a solution. Any ideas?

[imanaknut]

Welcome to the group !!! :welcome:

I would check to make sure the firing pin is not protruding too far out of the bolt. Does the serial number of the bolt match the number on the carrier and the rifle?

Also, which Maadi model? (ARM, RML, RPM, MISR-90)

[deth502]

i think id have to start with saying check the firing pin protrusion.

[5.0guy7]

You will have to forgive me as I am new to the AK 47. On the side opposite of the charging handle it reads ARM semi automatic rifle. From what I have read I think it is a pre ban gun, the mag well does not look milled out, it has a bayonet lug and the barrel is threaded and you can remove the piece on the end (flash hider?) The bot and carrier both match the serial number on the gun but the number on the receiver cover does not match. How would I go about checking the firing pin protrusion? What is to much or to little?

Hope this makes sense.

Thanks!

[deth502]

strip the rifle, take your bolt, push on the rear of the firing pin. it will stick out of the boltface. it should be about .060". if its much more, since you have changed the firing pin, which would rule that out, my guess would be that the hole in the bolt is peened out. probably the worst case scenerio in this instance. usually the metal in the fp wil get displaced first, and allow it to protrude too much because of that, or, the tip of the fp will become "sharpened" and will start punching primers are teh two most common/obvious problems, but changing the fp out pretty much ruled most of that out.

[5.0guy7]

What tool do I use to measure something so precisely? If the hole is peened out does that mean I need a new bolt?

[imanaknut]

deth502 gives good advice.

The reason I asked about the model was because I wanted to rule out a couple of versions that were problematic. The ARM was one of the better ones, they still had the threaded muzzles with just a cover tack welded to the front sight to prevent installation of the "evil flash hider" per George Bush the First. Somehow those tack welds magically broke allowing the owner to "de-Bush1" it. They had the ears ground off the bayo lug so that one of the other items that drove Bush1 crazy, a bayonet could not be installed. If the ears are still on the bayo mount of the gas block, is your rifle a Steyr import? That would make it a pre-ban and fairly rare. ACC/Intrac imported post-Bush1-ban rifles.

Asking about the serial numbers along with it being an ARM tell me that the head space is most likely ok. Soooo since you did replace the firing pin, and the new one did the same thing, there is the likelihood that the issue is the internals of the bolt being worn. I have a hard time believing that the bolt could be worn so much as to let the firing pin protrude too far as they were designed to fire over 25,000 rounds before the chance of issues, and the Egyptians were as Soviet as they could be.

There are many precision measuring devices available, but since the chance of you using an expensive micrometer or depth micrometer a second time would lead me to tell you to see if you could find a machinist who would be nice enough to measure it for you.

Check the internet for correct firing pin length as my brain is in shutdown right now for other personal reasons or I would be able to help. If your firing pin is of the right length, but it protrudes too far, you can file down the end so that it doesn't protrude too far. If it is a bolt issue, filing the firing pin would still be my first choice. Bolts for the semi-auto AKM, of which the ARM is one, are fairly easy to find, and not expensive, but you can then get into head space problems.

[5.0guy7]

I will look into finding someone to check the firing pin from me tomorrow. The bayonet lug is definitely there and functional, the gun came with one and it can be affixed to the lug. The gun is a ACC/Intrac import. On the underside of the receiver it has a 54?
Thank you all very much for your help. When I bought this rifle I thought it was a great deal and this guy really took advantage of me. Oh well you know what they say about Karma......
I will let you know what I find out about the firing pin, should I have the machinist attempt to shorten the pin if the find it to be too long?

[imanaknut]

Check online to verify the proper pin length. Once you have the correct numbers you can discuss it with the machinist.

I am trying to remember where there is a site that shows the proper firing pin dimensions, but for the life of me I can't remember. Getting old sucks, but it beats the alternative, assuming you can remember...

Good luck, and yes the ARM is the best of the post-ban Maadis, but the complete bayo lug is either a replacement gas block or something someone repaired by welding and shaping. Regardless, usually the Maadi ARM is a great weapon, and the problem you are having is probably the reason the previous owner got rid of it. Hopefully you got a good deal on it to make what you are going through worth it.

[deth502]

to guesstimate it, (holy shit, spellchecker didnt underline guesstimate, i guess it is a real word!) the thickness of a penny is just under 60 thou. (i measured 4 of them and they averaged .057-.058")

but, if you are going to have to do some grinding on it, its best to take it to someone who can measure the exact amount, as nut said. make sure that they know that it is a hardened/heat treated part, so as to not let it get overheated and loose its temper while grinding it.

i dont know the exact dims, and i dont have one in front of me to look at, but id guess the tip to be around the .060" range across as well, with a spherical end (round), or a rounded end (arced, like the tip of a pool cue) it should NOT come to a point or look anything like a pencil point narrowing towards the front.

[deth502]

just remember this repair if you have to replace the fp in the future, this will always have to be done. you dont even want to know the procedure for doing it proper and restoring the bolt, lol.

[5.0guy7]

Today I went two different places a friend of mine who is a mechanic and a local machine shop. We slammed the back of the bolt down on a steel table and checked it with a micrometer. Both of them checked the protrusion of the firing pin, and found it to be somewhere in the .057 to .061 range which from what members have said and what I have read online is within spec. So......WTF? What else would cause penetration of the primers? Does anyone have a next step idea?

To recap the problem. I will fire a few rounds (2 or so) when I fire a round and see smoke come out of the receiver it will cycle the bolt and chamber a new round. When I pull the trigger again it just clicks and lightly dimples the primer. I will find the previously ejected case and find that the primer on that case has been pierced. Then I will remove the firing pin from the bolt and find small pieces of metal which I assume to be parts of the pierced primer. When I remove those pieces I can get a few more founds before another failure.

[NAPOTS]

I was piercing primers in a brand new AR. I found that I had a little burr on the tip of the firing pin. I carefully stoned off the buff and its worked fine ever since. Can you try a different brand of ammo?

[5.0guy7]

I replaced the firing pin when this all started.....it currently looks/feels good with no burrs. I purchased some new ammo this evening and will head to the range tomorrow after work. Is it a bad idea to keep firing the gun even though it is piercing the primers?

[deth502]

youve already said that youve tried a few different types of ammo, so im assuming that you are not only using american commercial ammo.

you are using either steel cased or surplus brass, right?? american commercial brass has notoriously soft primer cups, and will often produce slamfires. it is also not too easy to find, and very expensive when you do, which is another reason ive been assuming that you havent been using it, but if you have, this is likely the problem.

[imanaknut]

I am going out into left field for this, but to others, what is the possibility that the bolt is worn to the point that it is too far forward during firing which is causing the firing pin to pierce the primer? There is almost too much right with the firing pin for that to be the sole problem assuming it is part of the problem and not just some poor bystander who just happens to normally be guilty.

[deth502]

I am going out into left field for this, but to others, what is the possibility that the bolt is worn to the point that it is too far forward during firing which is causing the firing pin to pierce the primer? There is almost too much right with the firing pin for that to be the sole problem assuming it is part of the problem and not just some poor bystander who just happens to normally be guilty.

i dont think your right, but i think you might be on the right track. the fp protrusion means that it will only come out of the bolt face that far. weather it is theoretically further beck, or "pushed up further" it would still only be able to extend a max of that amount from the bolt face.

id try to get your head space checked.

ive never seen or heard of a bolt moving forward, and in essence, lessening the head space and doing anything like this, HOWEVER, if the bolt is worn and causing EXCESSIVE head space, a common problem then would be pushing primers out, completely popping them, or flattening them (flattening occurs when the primers gets pushed out and then is forced back in under the pressure of the round.)

as nut said, out on a limb, but possibly with staked in or sealed primers, which are often found on surpluss/steel ak ammo, the pressure finds a weaker point in piercing the fp hole than it takes to push it out.

just thinking out loud here. hard to trouble shoot something when you cant actually see it.

[deth502]

btw, im sure its not safe firing a gun that is constantly piercing primers, but i will say that if it is in fact excessive head space, then i would be very wary of shooting it until thaqt problem was resolved.

[5.0guy7]

None of the ammo I have tried has been brass, all steel. I have tried TulAmmo, wolf and brown bear. All have had the same result. I do not thing I will shoot the gun again...I will take the gun to a local gunsmith ASAP.

[5.0guy7]

Got the maadi back from the Gunsmith today. He said that there was a "major" head-space issue that caused a over pressure condition which forced the primer to "bubble out" and that is why the firing pin punctured it. He had to totally replace the bolt to solve this issue. He was able to find a surplus unissued maadi bolt, and said that he checked the head-space and it is within speck now. I haven't had a chance to shoot it yet but plan to head to the range this weekend. He warned me that if I ever have a issue like this again to stop attempting to fire the rifle as it could have had a "catastrophic failure" and I could have possibly been injured.

Thanks for all the advice and help, I hope that this will help someone else someday if they are in this position.