Anyone ever have a mac 11 have a round explode before properly being chambered? I had a round jam and just blow up the bullet was just sitting in the barrel but the 9mm brass blown apart in front of the receiver. I noticed the round wasn't actually set off with the firing pin but it had a crease across the whole back of the round from not fitting right.
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SWD mac 11
- Thread starter mordeeb
- Start date
dcmdon
NES Member
just to repeat typeo's question. Open bolt?
More specifically there are 3 variants.
1) open bolt machine gun
2) closed bolt semi-auto
3) open bolt semi-auto - I'm not sure if it was this model specifically that at one time came in an open bolt semi-auto. The ATF told the company to stop making them this way because they were easy to convert to MGs.
Open vs closed bolt function fundamentally differently.
More specifically there are 3 variants.
1) open bolt machine gun
2) closed bolt semi-auto
3) open bolt semi-auto - I'm not sure if it was this model specifically that at one time came in an open bolt semi-auto. The ATF told the company to stop making them this way because they were easy to convert to MGs.
Open vs closed bolt function fundamentally differently.
dcmdon
NES Member
With an open bolt gun, there is not hammer, there is no moving firing pin. All there is is a little nub of a fixed firing pin on the breach face of the bolt. When the round chambers, the inertia of the bolt forces the pin into the primer. If the round is lined up with the barrel but stops before its fully chambered, it can go off when the bolt slams home. Because there is no hammer and movable firing pin, there is no way to make sure the gun does not fire out of battery.
Either way, here are my thoughts on a fix.
1) you should first try "buzzing" the chamber. Take a .45 ACP brass bore brush (not steel) and chuck it in a drill then spin it fast in the chamber for 30 sec or so.
2) if you want to actually shoot it rather than just admire it as an historical artifact, I'd suggest you go to max-11.com and buy one of Richard Lage's uppers for the gun. They work great. Not cheap. But good.
3) If you are shooting reloads, buy a chamber gauge and check all rounds to be used in the gun. Or run every one through a Lee Factory crimp die. You can back the crimp all the way out. If you do this, the die will just full length size the completed round.
Don
p.s. You didn't say if your gun was an open bolt semi-auto or a MG. It doesn't matter, the above applies to both.
Either way, here are my thoughts on a fix.
1) you should first try "buzzing" the chamber. Take a .45 ACP brass bore brush (not steel) and chuck it in a drill then spin it fast in the chamber for 30 sec or so.
2) if you want to actually shoot it rather than just admire it as an historical artifact, I'd suggest you go to max-11.com and buy one of Richard Lage's uppers for the gun. They work great. Not cheap. But good.
3) If you are shooting reloads, buy a chamber gauge and check all rounds to be used in the gun. Or run every one through a Lee Factory crimp die. You can back the crimp all the way out. If you do this, the die will just full length size the completed round.
Don
p.s. You didn't say if your gun was an open bolt semi-auto or a MG. It doesn't matter, the above applies to both.
I have a Max-11 and it shoots great just a little worried that the original upper had such a malfunction. Like I said the actually pin didn't strike the primer but instead it was just the force of the bolt itself. I guess I am lucky its 9mm and didn't ruin the lower.
warwickben
bubba Kalashnikov
I never under stood why they'd make a open bolt semi . It's like asking for problems. I know they can't be made that way any more. But allways thought it was odd they did.
Figure less tooling changes when the ATF shut off Meg's for us slaves.
Figure less tooling changes when the ATF shut off Meg's for us slaves.
one-eyed Jack
Manufacturer
I have touble understanding this. Jack.
sorry I guess I could describe it in person better and I should have kept the case or take a picture but think of the back of the case and instead of a normal puncture on the primer the whole back case had like a scar on it across the whole thing which set it off.
one-eyed Jack
Manufacturer
Did the primer have a scar across it too? That and a high primer might do it. Was it a reload? Jack.
dcmdon
NES Member
Mordeeb,
***Revised because I read the previous post****
3 questions, the answers of which will help a lot:
1) Describe the "scar" on the primer.
3) Was the Max 11 upper on it when you had the problem?
4) Semi-auto or MG?
Don
***Revised because I read the previous post****
3 questions, the answers of which will help a lot:
1) Describe the "scar" on the primer.
3) Was the Max 11 upper on it when you had the problem?
4) Semi-auto or MG?
Don
dcmdon
NES Member
There's no reason for it other than the fact that SWD already had a fire control system for their select fire M11. All they had to do was remove the full auto fire control parts and put some kind of spacer in so they couldn't easily be replaced, and voila, a semi-auto that they could sell.
One interesting note is that the manufacture of open bolt semi-autos was outlawed BEFORE the outlaw of the manufacture of new machine guns. The last open bolt semi-autos were built in 1982, at which time the ATF issued 82-8 and sent letters to a number of manufacturers. Machine guns were made through 1986.
Don
p.s. 82-8:
https://www.atf.gov/files/regulations-rulings/rulings/atf-rulings/atf-ruling-82-8.pdf
warwickben
bubba Kalashnikov
Yeah figured it was to save cash . I remember some of the story behind the open bolt semis . Barry from iraqvet channel talked about it in a video before he passed . He used to work for the guys that made the mac.
dcmdon
NES Member
Speaking as someone with an M11 with a Lage Max-11 upper, I'm guessing you don't use the stock upper very often. If you do want to keep using the upper, I'd suggest buzzing the chamber like I mentioned above. If you can find a shop or a gunssmith with a 9mm go gauge, I'd try that out in the gun to see if the chamber is sized correctly.
Short of that, its usually cheaper to buy a new upper for a M11 than it is to spend any money with a smith trying to troubleshoot it.
Short of that, its usually cheaper to buy a new upper for a M11 than it is to spend any money with a smith trying to troubleshoot it.
one-eyed Jack
Manufacturer
1. Knock on wood. 2. My MAC .45 has been running fine since new in 1990. Makes me think about running it with the brass catcher, just in case. Jack.
It's an obvious question, but have you cleaned the chamber recently? Sounds to me like the round got stuck out of battery.
I'm not intimately familiar with the mac-11, but i suppose a problem with the bolt guide/spring could cause this to happen too.
I'm not intimately familiar with the mac-11, but i suppose a problem with the bolt guide/spring could cause this to happen too.
warwickben
bubba Kalashnikov
Ill have to try that mac out of you bring it to the next shoot.
one-eyed Jack
Manufacturer
If hell does not freeze over, I'll bring all the subguns and suppressors to the next shoot as usual. Jack.
dcmdon
NES Member
Its definitely possible. Thats why I suggested chucking a .45 ACP brass cleaning brush into a drill and "buzzing" the 9mm chamber.
warwickben
bubba Kalashnikov
Cool I think if I shot that one I shot all your 45's besides the pistol resling (for get the spelling)
one-eyed Jack
Manufacturer
My MAC was assembled new with the spring guide ass-backwards. Only realized it when it failed. Got a new original one and now all OK. Jack.
