When does the US Army consider the grease gun safe

[jim c 351]

According to Dept of the Army, TM9-2210, the SMG M3/M3A1 is only considered safe when the mag is removed and bolt foreword.

The fear is if dropped, the cover(safety) may jar open and the bolt may travel to the rear and chamber a round.

Jim c

[StrangeRanger]

"Now you're killin'. Now you ain't" seems a whole lot simpler.

 

Seriously though on John's M3 the port door is held pretty firmly in place (unlike the one in the current thread.) It would take a very unusual impact to both open the door and drive the bolt back till it chambers a round. If the gun is in good repair I would regard the TM as being overly cautious. I wonder what the corresponding FM says about operating conditions.

Edited October 25, 2019 by StrangeRanger

[yohuang]

The door does not have a positive lock, totally depends on friction... that's not a great design. Those MP40 and STEN with improved push-down bolt handle safety was better.. the lock is positive on those.

[StrangeRanger]

Except you are basing your comments on your gun on which the safety is malfunctioning. When working properly the spring holds it in either position until you move it by hand to the other. It does not flop around and it does not spontaneously open.

 

These guns are over 70 years old, stuff wears out, springs lose temper. If you're not comfortable with doing the repair yourself, find a gunsmith to remove the rivets, replace the spring and re-rivet it.

[Got Uzi]

When the bolt is locked open and ready to fire, close the door and there is positive tension against it due to taking the bolt off the sear. Maybe I have an odd M3 that keeps on working

[StrangeRanger]

But it needs the spring tension to keep it in the "Now you're killin'" position. That's what he needs to fix

[yohuang]

Yes. Just applied a very thin layer of eproxy coating on the hinge. If this spring tension comes back because of this, I will do a more permanent fix. It takes a few hours for the coating to cure, I will know by tomorrow.

[StrangeRanger]

That will not restore the spring temper

[yohuang]

That will not restore the spring temper

 

No. It won't change the spring. I carefully thought about the situation: two parts are relevant -- the spring and the door.. The spring is a fixture on the frame, changing the spring is mission impossible without damaging the original rivets. So, that path is a dead end. The door is removable, using a copper punch and a rubber mallet, I easily moved the door off from the frame. if the door hinge can be adjusted a little bit (e.g. 1/10 of a millimeter larger), the hinge will run against the spring again and the spring tension will come back. That's the theory. Current coating is just a temporary measure to prove this theory before adjusting the geometry of the hinge.

 

[Edit] Actually, the spring can be modified. I cannot do it, but professionals can do it -- they can add a little bit steel on the top edge of that flat spring without damaging the finish of the neighboring area. I watch how they fixed other things in the past, they had special micro-TIG and laser welding equipment and they did the work under magnifier. However, that would cost much more. Enlarge the hinge should be easier.

Edited October 26, 2019 by yohuang

[Black River Militaria CII]

If you want to increase the OD of the hinge, just make a mandrel that is slightly larger than the current ID of the cover hinge hole and drive it through. This will expand the OD of the hinge to provide a bit more friction against the spring to keep the cover in the positions needed. If it is not enough to hold the position of the cover, again make another slightly larger mandrel and expand the hinge more.

it is ironic that you are against replacing the hinge spring due to the riveting, a cosmetic issue, but would apply a messy and ineffective epoxy coating to the outside of the hinge. I don't get that at all. Epoxy is a cheap and really bad "fix" and will quickly wear off.

[StrangeRanger]

...and enlarging the diameter cover hinge sleeves will necessarily loosen their fit on the hinge pin. That could be a real trip down the rabbit hole. Rivets are a service part. Service the gun properly by replacing the spring with one that works and re-rivet it. You've probably got something like $20K invested in the gun. Why do a half-assed repair.