Grease gun M3/M3a1 Rear Welds

[komodoj]

So what is the census on the rear welds cracking/Spliting on Grease guns? People talk about how the rear of the guns taking a pounding during bolt travel and breaking welds? Whats the Truth in this. I know this has been discussed here somewhere but wanted to start a new thread. Thank you in advance.

[StrangeRanger]

M3s not so much, the M3A1 has a smaller guide rod plate resting against the rear of the receiver and are more likely to deform/crack due to the impact being concentrated in a smaller area.

Quick fix = install the plate from an M3.

Got Uzi will probably be along with more input shortly, he's way more expert at these guns than almost anybody. He's got a mod to the M3 plate in an M3A1 that aids in disassembly

[NFA amnesty]

I purchased my M3A1 guide lamp and the entire rear receiver was replaced with an end cap welded all around the diameter. I can speculate it was from damage to the rear of the receiver. It could be how it was deactivated, but consensus with most folks I have talked to state that would not have been how a grease gun would have been deactivated.

 

Got Uzi is the expert as he shoots thousands of rounds each year from his grease gun. If I recall he replaces the springs every 5k rounds of shooting. The rear of the receiver can and will be damaged if you use the m3a1 plate and not change out the guide springs. If you look at various pictures of grease guns on the web, a lot of them have the rear bulging out.

[johnsonlmg41]

One needs to keep in mind these were never designed as 100K round shooters. Combat guns like this rarely broke a few thousand rounds before "something" happened and the war was over or the gun was out of service for various reasons. The concept was quantity vs. spending too much on Thompsons. 5 guys with grease guns always beats one guy with a Thompson for the same money (I don't recall the actual costs but you get the idea).

[komodoj]

Thanks guys for all the great replys. Reached out to forum member Got Uzi and got some great recommendations from him. Hes a true asset and has outstanding knowledge of grease guns. Glad he is here to help!!

[Got Uzi]

Good evening and I must say-thank you for the kind words. It means a lot that people seek me out as Im one of the few who have ran the Grease Gun platform hard for several years.

 

Yes I would change out my recoil springs every 5k or if the gun was feeling off when you shoot something long enough, the gun will tell you if its not happy lol

 

Blown out backs are from gun abuse being any number of the following-lack of spring care, running an M3A1 guide rod plate with lack of spring care (even worse) lightening a 45 bolt to make it into a speed bolt or the best one-running Thompson recoil springs to get it to really run. Any number of those stupid user tricks can or will result in back of guns being cracked, blown out, holes egged or flat out ruined.

 

Johnson is correct in saying that this weapon platform was meant to see MAYBE 3,000 rounds in its service life and be rebuilt or even replaced. They were NEVER meant to be around, let alone being used nearly 80 years later. It really says something for the design doesnt it?

[dalbert]

My very good friend has a Medea M3A1 that has developed rear cracks. I dont know the specifics of the springs, etc., but he has owned it for at least 25 years, and the cracks developed slowly over time. Hes been meaning to repair it, and Im pretty sure his round count is low.

 

Just my $.02

 

David Albert

dalbert@sturmgewehr.com

[Got Uzi]

David,

 

The Medea guns varied as to who actually made them. Those guns espically were prone to blowing out the back as Ive not seen many put together well or bad welding there. I had a Medea that someone put a 1/2 thick nylon buffer in the back of the Guide Rods to soften the blow of the bolt. It worked but it also sped the gun up which speeding up an M3/M3A1 can lead to the same issues we are discussing.

 

Ive never had a test done on the grades of sheet metal used between the Guide Lamp, Ithaca, and Medea guns but it would be interesting as Id bet it would be a similar issue to the material differences between a Colt or GI Thompson and a WH

[Blanksguy]

I don't believe that .45ACP +P ammo helps with cracking welds.........I just use standard .45ACP "Ball" ammo and my M3 runs great.

[huggytree]

Would an integral silencer reduce recoil and make the welds last longer?

 

Bleeding off some gas w the Swiss cheese barrel I would think would soften the recoil. Sure seems that way.

 

I think medeas may be made of softer steel than guide lamp.

[Got Uzi]

Its not the welds that normally crack its the actual steel sections of the receiver and think on something-you are restricting the gas of the fired round through a suppressor and you think that will slow the bolt speed backward? Its actually the opposite. By restricting the gas from the fired round, you are creating more back pressure which in turn can and will increase your bolt speed to the rear. Ever notice the extra gas when shooting suppressed coming out the ejection port? Thats why...shoot an M16 set up identical with and without a suppressor then youll really see the difference in speed. Bolt speed equals cyclic rate which translates to more wear and tear

[huggytree]

On a normal suppressor I 100% agree. But Im not sure about integral. Theres lots more space for the gasses. Plus its venting out the barrel sides itself. Slowing down the bullet . I dont see the heavy gas coming out the ejection port like I do with normal suppressors. I may be speeding up the rof. Ill have to time I both ways. Speeding up the bolt could be short stroking it too. Less recoil. Perceived recoil is way less. Its my only integral can. Im no gunsmith. Just a shooter Edited May 3, 2021 by huggytree

[Got Uzi]

Well Im a gunsmith and shooter. Faster bolt speed equals faster cycling. Faster cycling doesnt equal short stroking. Short stroking is from lack of blowback.

 

Felt recoil reduction is due to the big ass weight on the front adding mass to the gun making it easier to absorb recoil

[komodoj]

Well Im a gunsmith and shooter. Faster bolt speed equals faster cycling. Faster cycling doesnt equal short stroking. Short stroking is from lack of blowback.

 

Felt recoil reduction is due to the big ass weight on the front adding mass to the gun making it easier to absorb recoil

 

Easy on Huggytree. Hes a world Renown gunsmith and mechanical engineer. He practically invented the Suppressor and if he talks we all need to listen. I for one value his expertise and extensive knowledge!!!!!

[Got Uzi]

A lot more spaces for gas on the first few rounds but the expansion chambers fill quickly on bursts and then it bleeds back into the guns as it has no where to go. But what do I know....Im just a moron who works on vintage guns and shoots them well.....

[Grease Gunner]

Komodoj, on 03 May 2021 - 13:20, said:

 

Easy on Huggytree. Hes a world Renown gunsmith and mechanical engineer. He practically invented the Suppressor and if he talks we all need to listen. I for one value his expertise and extensive knowledge!!!!!

 

 

Not Only that He invented the concept of thread crapping

Amazing that he finds time for his hobby ,,,,,Plumbing

I too have learned many vauable thiongs from him

[Got Uzi]

Is this a sign the board is fed up with the level of stupid coming from someone? Im not sure, but if I were to take a guess, he has the same substance floating around in his head as the septic tanks he works on at this point.

[Grease Gunner]

When is the board going to follow UZITALK lead and ban this nonproductive braggart snobbish opinionated jerk

who does nothing but denigrate this forum with his prattle???

[johnsonlmg41]

Hey now....I've repaired septic tanks (from the outside). I actually have the equipment and plumbers have called me to do the work, and it's profitable LOL.

I'm not on uzitalk, but have seen it searching from time to time, and I can't imagine how you would get banned on there? The backstory has to be amusing, so if you have to, PM me the amusement if it's not repeatable here?

Seems to be a lot of amusing threads getting pulled here lately, sadly I'm sure I'm missing out on the humor.

[Rekraps]

Well I'm new to this Forum, and own a gorgeous M3 (100% restoration by Andrewski) AND I purchased an integral suppressor from Joe at Curtis Tactical (see Machinegun Mike's youtube video). The cyclic rate of fire for the gun is identical (at least to my ears) with or without the can. I run only military or commercial 230 grain ACP through it.

 

With the integral, it is an absolute pleasure to shoot, as quiet as a .22 with can. An amazing piece of engineering.

 

As far as everyone getting their feelings hurt, really? The reason we have a forum is so that everyone can express their opinions, and most importantly, their EXPERIENCE with the various SMG's.

 

I collect open bolt SMG's and to me, the hardest thing with the hobby is acquiring all the "extras", like magazine loaders, spare bolts & springs, extractors etc. For each gun I own, I make sure to have plenty of spare parts, as the market will, and is, drying up for OEM factory parts.

 

BTW, if you don't want to invest in an integral suppressor for the M3, Jason at Indianapolis Ordnance was kind enough to cut down an OEM M3 barrel to 5", thread it, and have it parkerized to perfectly match my gun. So now I have a choice of the integral can or direct mount with separate can.

 

Glad to read all the good stuff....

[Mike Hammer]

Who is the best source for M3 springs, I think I would like to change mine out. Does anyone have NOS originals?

MH

[Got Uzi]

I bought up on them a few years ago. Sarco used to have a pile of them at the Creek.