M2 Carbine Timing Question ...

[HB of CJ]

Just changed out my NFA M2 Carbine "Trigger Pak" to another donor USGI Carbine. The slide trips the "rocker" a little bit early for my satisfaction. Not the same free travel distance as in the earlier Inland donor carbine. This barrel ALSO has an integral gas block assembly and the piston nut bottoms out tight a LITTLE LESS DEEP. I would be more happy with a little bit later timing.

 

This specifically means more slide free travel before the rocker is tripped.

 

Wondering how to do this? In the past we have actually cut and splinted longer the rocker a few millimeters to establish a safer condition. Has anybody taken a USGI trip lever, (rocker) and slightly ground down both ends to delay the hammer drop any? What would be considered the minimum amount of SAFE slide free travel after the bolt locks up completely?

 

Thanks in advance. Sweet little buzz guns when set up and tuned correctly. All Oregon State, US Code Laws And NFA Rules Apply.

 

Edited by HB of CJ. Poor proof reading my part. My apology. The rifle is probably safe to shoot full auto. My desire is to make the little rifle more safe in full auto. Thus the lengthened slide free travel after the bolt has locked up totally. Thank you.

Edited September 10, 2016 by HB of CJ

[Black River Militaria CII]

Keep in mind that bolt velocities are a factor in the timing of the ignition in full auto piston operated actions.

[emmagee1917]

Not an expert , here , but I would refile the contour of the slide to push the rocker down later than normal .

Chris

[jim c 351]

HB,

Are you saying the hammer drops before the bolt has completely rotated to fully locked.???

Hard to visualize how this happens.

Or are you saying the bolt is locked but the slide isn't all the way foreword when the hammer trips??

Jim C

Edited September 10, 2016 by jim c 351

[HB of CJ]

Clarifications and thank you. I have NOT fired the rifle. The bolt is always fully locked up. Mass production. Interchangeable parts variation?. The donor Carbine is an Mix Master Inland 5129XXX. Mint condition. Everything looks OK. Barrel index looks perfect. Mint muzzle, bore and throat. Barrel is straight. Parts installed correctly. For some reason the slide trips the hammer slightly sooner than in the old Inland donor gun. Old MM Inland had the swagged gas block. New Inland has an integral gas block.

 

Just about 1/16th on one inch sooner. Not much. But enough that the slide has slightly less free travel. This is the distance between observed bolt lock up to the hammer dropping while in the full auto function. Does anybody know from USGI specifications how much slide free travel is the minimum distance? The sweet distance? The maximum distance? I do not think the rate of fire would be directly affected. I can not find this info in the various Carbine books. Safety first. Thought I would ask here first.

 

All Oregon State US Code Laws And NFA Rules Apply.

[n64atlas]

Are you using the same slide with the kit?

same bolt?

[HB of CJ]

Different Carbine. Different round USGI bolt. Different USGI M2 slide. The trigger pak is the entire assembled M2 trigger housing using its own trip lever. I understand, that the piston must be VERY near sitting on the bottom of the gas block hole for the gun to work? The piston needs the full distance of operation to properly act against the slide? More so with M2 operation. More happens. No problem in semi auto. In full auto the timing must be very close or the little fun burp gun will not cycle right.

 

Short stroke piston gas operation. What I am doing right now is inverting the gun out of the stock muzzle up while hand test cycling the M2 function watching the point where the slide drops the hammer WHILE ALSO at the same time trying to listen or "feel" when the extended piston first kisses the slide then trying to eyeball the distance the piston continues before the hammer drops. Which happens first? The hammer dropping or the piston fully seating inside the gas block? It should happen very close together.

 

Like already said by B R M C, (thank you) it takes a little bit of time for the hammer to drop, pop the primer, the powder burn, the bullet travel, the gas port exposed and the piston being slapped by high pressure gas, thus kicking the slide back and firing the gun in full auto. The piston SHOULD be at full rest before the hammer drops? The piston needs maximum velocity to work the gun. A late type nut is being used.

 

Most likely a combination of a different receiver, a different barrel, a different slide and a piston nut that torques up tight with about one full additional amount of thread showing. The nut and gas block threads look excellent. I am using about one strong index, (second knuckle) finger's worth of torque on the piston nut wrench when tightening it up. Easy to over torque and strip out the threads. Do not ask me how I know this to be true! Embarrassing. Long time ago also. Anyhow, will advise. M2 Carbine knowledge.

 

All Oregon State, US Code Laws And NFA Rules Apply. I am sure I can get the new donor gun running 110% with full power ammo. A FUN hobby endeavor.

[n64atlas]

I would swap the slide out and see if the timing improves. The cam area sounds like it is longer and hitting lever quicker than the old slide. I wouldn't

grind on the lever especially ir it is the registered part.

[HB of CJ]

I will try different combination of parts, starting with some different M2 USGI slides I have. The USGI M2 trigger housing is the registered NFA part. Rare. Probably a combination of little things. Or ... since the little rifle does have quite a bit of slide free travel all ready I might test fire safely. Might find out everything works fine as is. I still have much to learn about M2 Carbine function. What looks not quite correct in static function and timing testing might not be the case with dynamic shooting. Must wait until the weather cools off and we perhaps get some monsoon rain. The shale quarry is still way too dry. Will advise. Much Fun.

 

All Oregon State, US Code Laws And NFA Rules Apply.

[n64atlas]

If you get jamming in full auto, it might be the magazine spring not keeping up with the carbine. That is way it works fine in semi-auto and not full. Wolff makes some mag springs to replace

a worn out one. They are supposed to work well
https://www.gunsprings.com/M1%20CARBINE/US%20M1%20CARBINE%20/cID2/mID98/dID163#536

[dalbert]

If you get jamming in full auto, it might be the magazine spring not keeping up with the carbine. That is way it works fine in semi-auto and not full. Wolff makes some mag springs to replace

a worn out one. They are supposed to work well

https://www.gunsprings.com/M1%20CARBINE/US%20M1%20CARBINE%20/cID2/mID98/dID163#536

 

That's good advice from n64atlas...

 

David

[emmagee1917]

We've been down this road many times before ......there is not nor has there ever been a registered trigger pack for the M2 Carbine .

You either have a registered reciever or you have a kit .

The kit , by BATF regulations , consists of seven parts ...

1) selector lever

2) rocker assembly ( actually three parts rived together , but BATF calls it one part )

3) M2 full auto hammer

4) Full auto disconnect

5) Disconnect plunger

6) Disconnect spring

7) selector lever " 9" spring.

 

These are the kit . The kit's serial number MUST be on one of these . MOST use the rocker lever because it is large and soft , but some have used the disconnect . The trigger housing is not nor has ever been part of the "kit " and any numbers on it are not " illegal " to be there , but DO NOT satisfy the BATFs marking requirements . A part of the legal kit MUST be marked .

The trigger housing , the round bolt , the M2 sear , the M2 slide and the M2 stock are not nor have ever been a legal , defined part of a kit . That is why you want to modify these and not the rocker IF THAT IS THE NUMBERED PART because you legally can not replace it nor have spares in your possession .

 

Chris

[HB of CJ]

emmagee: Respectfully, that happens not to be the case. Flemming registered M2 Trigger Housing. A few on the roles. PEM me if you need specific information. Respectfully.

 

PS; Respectfully; Our collection of USGI rockers are very hard spring steel. Impossible to just file. Difficult to cut or drill. Must be ground. They are most certainly not soft.

Edited September 11, 2016 by HB of CJ

[jim c 351]

Chris,

If you feel that someone at the ATF violated federal law by allowing a carbine trigger housing to be the registered part, perhaps you might consider petitioning the Justice Dept to form a grand jury so as to indict and try said ATF employee in Federal court.

Please keep us informed as to progress you and Loretta Lynch are making.

Best of luck.

Jim C

PS if I were to buy a registered M2 kit the only one I would consider is an ATF registered trigger housing.

[n64atlas]

Back before the MG ban, I don't think ATF cared where the stamp was. Later they defined it as parts ONLY used in the M2 carbine. The Housing was can be used on a M1 carbine and is found

on most rebuilds. The military converted lots ob M1's to M2's during the Korean war. The DCM sold these for years, with those trigger housings. They couldn't just outlaw all the trigger housings

that had the 9 spring cut.

[emmagee1917]

Here we go again . Really , with all due respect , we've hashed this about a half dozen times . Wishfull thinking does not change the rules . Go here :

https://www.atf.gov/file/58196/download

Page 12 lists the contents of the kit .

If you say the M1 Carbine trigger housing has been added , PLEASE list the BATF site where that can be found .

Until then , it's just wishful thinking to cover up all those illegal kits that are not properly marked .

Don't want to be aggressive or a smart-*** , just trying to help.

Chris

[jim c 351]

Suggest you contact Loretta Lynch and have the ATF scoundrels indicted.

Imagine the nerve of the feds, approving something one day and then disapproving it the next.

Jim C

[emmagee1917]

I don't know who Loretta Lynch is and I don't really care .

BTAF approved the adding of the trigger housing ....where ?

Please post a link to the letter and I'll apologize .

Chris

[HB of CJ]

My apologies to all. This thread has strayed and decayed. (E)emmagee1917: Respectfully, the fact remains that I do have a legal current BATFE tax stamp on my Flemming M2 Carbine Trigger Housing. It also "covers" the "Seven, (7) Deadly Sins" specific M2 parts. This legally is no different from that of a legal NFA transferable M2 stamped receiver M2 Carbine Rifle which ALSO has the seven specific parts "covered". If one requires a specific ruling letter from the BATFE, it would be easy for one to obtain. Any other side steps or distractions from the specific M2 timing discussion at hand may detract from this Excellent Forum. Again, my apologies. Respectfully. HB of CJ

 

All Oregon State, US Code Laws And NFA Rules Apply

Edited September 14, 2016 by HB of CJ

[dalbert]

Yes, let's focus this discussion back on the M2 timing issue. The trigger housing is one of those situations where folks should probably agree to disagree, and set it aside.

 

David Albert

dalbert@sturmgewehr.com

[n64atlas]

Back to the perceived problem. I don't think you really have one. The thinks that would change the timing are the rocker , spring, and slide. Piston only opens the bolt by hitting the slide. You can't bench test that function. Get the calipers out and measure the two cam areas on your slide inventory or just use the slide from the other carbine, See if the timing is more to your liking. I really don't think it matters all that much as the pressure should have dropped enough by the time the bolt unlocks. Make sure your recoil spring in new so the bolt is slowed properly. Rate of fire is 750-775 for a reason.