Pulling bolt back while on safe?

[Old Soldier]

I observed a couple of "jams" on the range with FA Open bolts.

We pulled two MACs off the line due to "malfunctions". The shooters never got a round off.

The first was a MAC10 in 9mm, that was on safe with the bolt jammed half open. I was asked to help out. I was not able to move the safety or pull the bolt back. I removed the retaining pin and the upper receiver. I then reassembled the weapon and successfully performed a complete functions check.

Then a M11/9 came back for the same problem (on safe, bolt stuck hallway back). This weapon had the LAGE MAX31 MK2 upper and upgraded with the LAGE hardened sear, hardened safety, extended safety lever, and improved trigger group. Again, the upper was removed, reinstalled and a function check was performed.

It appears that the shooters tried to pull the bolt back with the weapon on safe or not fully off safe causing the bolt to jam halfway back.

is my take on this correct?

My UZI bolt will not move at all while on safe.

Is this a problem with the MAC design which allows the shooter to move the bolt back while on safe until it jams. At this point the safety can not be moved to the fire position.

Pat.

 

[ChuckB]

You cannot put these on safe with the bolt closed. Just a design "feature".

 

[sniperdoc]

Many firearms(M1911, m16, are probably the most famous) require the weapon to be "cocked" before the safety can be Applied.
I realize that most Ranges cannot afford a Manual for every possible firearm that may be brought there; but maybe require each weapon to be accompanied by a copy (printed from internt?)

 

[timkel]

A good thread on the Ingram safety.

http://www.uzitalk.com/forums/showthread.php?78319-MAC-Idiosyncrasies&highlight=ingram+safety

 

[root]

On the MAC 10 just turn the cocking knob with the bolt forward and chamber empty.

Rich

 

[LawBob]

I observed a couple of "jams" on the range with FA Open bolts.

We pulled two MACs off the line due to "malfunctions". The shooters never got a round off.

The first was a MAC10 in 9mm, that was on safe with the bolt jammed half open. I was asked to help out. I was not able to move the safety or pull the bolt back. I removed the retaining pin and the upper receiver. I then reassembled the weapon and successfully performed a complete functions check.

Then a M11/9 came back for the same problem (on safe, bolt stuck hallway back). This weapon had the LAGE MAX31 MK2 upper and upgraded with the LAGE hardened sear, hardened safety, extended safety lever, and improved trigger group. Again, the upper was removed, reinstalled and a function check was performed.

It appears that the shooters tried to pull the bolt back with the weapon on safe or not fully off safe causing the bolt to jam halfway back.

is my take on this correct?

My UZI bolt will not move at all while on safe.

Is this a problem with the MAC design which allows the shooter to move the bolt back while on safe until it jams. At this point the safety can not be moved to the fire position.

Pat.

The safety is designed to be activated when the bolt is engaged (back).

Do not put it on safe when it's already in a safe position (bolt being forward). Because there is no movable firing pin on the m10/11, with the bolt forward the safety has no function. Put another way: If you have a live round chambered, and the bolt closed (forward), the safety won't do anything to help you - you're just in hope mode.

Therefore, if you pull the bolt back, while put on safe, it will put the sear/trigger/bolt in contention - freezing it, if you will.

 

[DistalRadius]

Engaging the safety with the bolt closed does prevent the bolt from retracting far enough to chamber a round if dropped or slammed on its rear, once a common cause of concern with OB subguns. So there is that usage, however dubious.

The M-10s rotating cocking knob bolt-lock is a much more elegant solution IMO.

 

[SecondAmend]

Add the Thompson models 1921 and 1928 to the list of open bolt SMGs where you have to cock before the safety can be moved to the 'safe' position.

 

[Old Soldier]

Thanks all, for the comments. So, a design flaw! If you pull the bolt back when the safety is on it can cause the the bolt to get stuck in the halfway open position.

So, just don't do it! Easy!

 

[Adolf]

Root,

That was what I was shown to do by a person that used mac's during Vietnam!

 

[root]

That's why they have the slot in them not just for the sites but the slot " | " fire. Slot this way " -- " safe.

I don't think I ever used the receiver safety on my gun.

It's natural once you get in the habit of twisting the knob with the bolt forward.
It also keeps people that are not familiar with the gun from charging the bolt to live.

Rich

 

[sniperdoc]

The safety is designed to be activated when the bolt is engaged (back).

Do not put it on safe when it's already in a safe position (bolt being forward). Because there is no movable firing pin on the m10/11, with the bolt forward the safety has no function. Put another way: If you have a live round chambered, and the bolt closed (forward), the safety won't do anything to help you - you're just in hope mode.

Therefore, if you pull the bolt back, while put on safe, it will put the sear/trigger/bolt in contention - freezing it, if you will.

How could one safety close the bolt on a live round?
How would one fire that chambered round?

 

[Hey]

How could one safety close the bolt on a live round?
How would one fire that chambered round?

Question 1) remove the magazine first. That's the only way. You can't close the bolt on a live round on an open bolt as the firing pin is fixed ready to strike.

Question 2) Open bolts don't "chamber" a round until the millisecond before its fired. If the bolt is back and there was a round sticking out of the barrel/chamber due to jam or you placing it there, to fire you simply pull the trigger releasing the bolt to fly forward which hits the primer and "Boom".

 

[sniperdoc]

Question 1) remove the magazine first. That's the only way. You can't close the bolt on a live round on an open bolt as the firing pin is fixed ready to strike.

Question 2) Open bolts don't "chamber" a round until the millisecond before its fired. If the bolt is back and there was a round sticking out of the barrel/chamber due to jam or you placing it there, to fire you simply pull the trigger releasing the bolt to fly forward which hits the primer and "Boom".

Exactly. But the other post,@least the way I read it, seems to indicate this could be done!
Maybe he was referring to a Closed Bolt rather than open bolt gun?

Without a separate Hammer or Striker, the gun couldn't fire unless you dropped it or hit the cocking handle, right?


I'm certainly no MAC Expert, but I've shot plenty of Open Bolt guns in the Military, & none of them could close on a live round.

(The BAR can; in Semi Auto, it fires from Closed Bolt, Full Auto is Open Bolt. But that is entirely different! )

 

[LawBob]

How could one safety close the bolt on a live round?
How would one fire that chambered round?

I take you it that you meant safely, not safety.

Well, you could ease the bolt down (safeLy?) on a live round. I never said it was safe - only that it might not go off.

And if it didn't go off, engaging the safeTy isn't going to make it safe. Sorry if my point wasn't clear.

 

[LawBob]

Question 1) remove the magazine first. That's the only way. You can't close the bolt on a live round on an open bolt as the firing pin is fixed ready to strike.

Question 2) Open bolts don't "chamber" a round until the millisecond before its fired. If the bolt is back and there was a round sticking out of the barrel/chamber due to jam or you placing it there, to fire you simply pull the trigger releasing the bolt to fly forward which hits the primer and "Boom".

1) you don't have to remove the mag. Just ease the bolt and let it chamber slowly. I've don't it testing feed ramps.

It's a really stupid and dumb way to do it but, like cleaning with gasoline, it works. If you let the bolt all the way down on the round, if there's enough pressure it will go off, but might not.

2) this is why alum case ammo is highly discouraged for open bolts- more likely to get a non extraction and then an OOB.

As to the original question: you can't. It's not designed for this closed bolt type firing.

The point of this was that the safety wasn't designed to help at all when the bolt is closed due to the mechanics of open bolts.

It's not a design flaw any more than not being allowed to engage the slide safety on a 1911 when the slide is locked back is...

 

[TonyM]

I've don't it testing feed ramps.

I assume you mean you've "done it testing feed ramps"?

 

[Hey]

I assume you mean you've "done it testing feed ramps"?

Live ammo slowly testing feed ramps on an open bolt gun...

Thats the dumbest thing I've ever read yet nazi had the gall to ruin a whole thread with stupid fire pictures?

 

[LawBob]

I assume you mean you've "done it testing feed ramps"?

Clearly that's an auto correct. Try it.

 

[LawBob]

Live ammo slowly testing feed ramps on an open bolt gun...

Thats the dumbest thing I've ever read yet nazi had the gall to ruin a whole thread with stupid fire pictures?

Key difference:

1) I didn't advocate people to do this, unlike an idiot who said wash with gasoline.
2) I said it was not safe, like washing parts with gasoline.