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M1A1 blows gas out the back end into my face


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Its so wierd, I have shot at least 10 thompsons, 1928s and m1a1s and only this one does that,

Its like someone blowing air into your face, not a lot but enough to make me squint as I shoot

I am going to look at the buffer. Any board members have an answer?

Its not obvious to me

Thanks

 

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Both my '28s do that too....but I run them wet so get a mouthful of CLP fir the first couple mags after I oil them up.

Just that all the parts are snug and well-machined....add oil and they're going to seal and act like a piston compressor.

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Hi,

 

My M1's do that all the time. More than the top-cockers. The top-cockers have the groove in the sides of the receiver. I leave the felt at home. That allows the 21s or 28s to breath down the sides. The M1/M1A doesn't have the extra vent slots. When I oil them up I get quite a squirt of air out the back.

 

Nature of the beasts in my experience.

 

YMMV,

 

Grasshopper

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You're shooting left handed, huh? So do I. After my M1 has blown the last of the excess lube and CLP into my face, I hardly notice the blow-back. Shooting glasses a must.

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As the oil blow back is inherent to the Thompson, this may not be permissible for competition shooting in "original configuration" class shoots. On Model 1921 and 1928 sized pilots (I don't know if the M1/M1A1 pilot is the same diameter) a no. 36 o-ring stretched over the pilot protrusion out of the receiver and slid snug against the back of the receiver is pretty effective at turning much of the spray into a dribble. The dribble can occasionally be wiped off the receiver and frame.

 

I did come up with a shield that adds even more protection from the oil, but I believe the o-ring alone is sufficiently effective for most shooting.

 

Enjoy your Thompsons, and shoot safe.

 

MHO, YMMV, etc.

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As the oil blow back is inherent to the Thompson, this may not be permissible for competition shooting in "original configuration" class shoots. On Model 1921 and 1928 sized pilots (I don't know if the M1/M1A1 pilot is the same diameter) a no. 36 o-ring stretched over the pilot protrusion out of the receiver and slid snug against the back of the receiver is pretty effective at turning much of the spray into a dribble. The dribble can occasionally be wiped off the receiver and frame.

 

I did come up with a shield that adds even more protection from the oil, but I believe the o-ring alone is sufficiently effective for most shooting.

 

Enjoy your Thompsons, and shoot safe.

 

MHO, YMMV, etc.

Have you tried to put the O ring inside the receiver?

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I think you guys might be putting to much oil in your guns. We shoot 21s, 28s and M1s on a fairly regular basis and the only time I see this happen is when somebody gets a little over zealous with the oil. When I clean my guns I put a very small dab of lubricant on each face of the bolt and wipe it with my finger to spread a thin film where the bolt slides against the trigger frame and receiver. 21/21 actions also get a drop of oil on each pad after cleaning.

 

My trigger frame components are usually left dry. You can use a cloth with a very small amount of oil to wipe lubricant on trigger frame components when you disassemble for cleaning. Excess oil here just creates gunk from powder residue and carbon.

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Can you use gun grease on the bolt or do you guys recommend oil? I someday will receive my M1A1 when the ATF NFA Branch decides I am worthy enough to have my stamp. Of course at almost 10 months and not assigned to an examiner yet, could be in for a very long wait.

Edited by NFA amnesty
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On my M1 I grease the recoil spring and add oil, smear a little grease on the top, bottom and sides of the bolt and add oil, oil the hammer and firing pin. Lately I've been using CLP. Yes, I wear shooting glasses and yes, they get wet.

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For what its worth, do not use grease on/in the trigger frame. The disconnextor (the little lever

that fits in the trigger) spring is a very weak spring since all it is designed to do is flip the disconnector

out from under the sear lever. It is not strong enough to overcome grease. We recently had a gun

in here that "didn't work" and the owner had loaded the trigger frame with thick white moly grease

which completely clogged the disconnector. All we had to do was degrease it and it worked fine.

 

Bob

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For what its worth, do not use grease on/in the trigger frame. The disconnextor (the little lever

that fits in the trigger) spring is a very weak spring since all it is designed to do is flip the disconnector

out from under the sear lever. It is not strong enough to overcome grease. We recently had a gun

in here that "didn't work" and the owner had loaded the trigger frame with thick white moly grease

which completely clogged the disconnector. All we had to do was degrease it and it worked fine.

 

Bob

Great info on what not to do. Thanks Bob.

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