DINK

Damn- every M60 owner's nightmare. Thanks for the info.

Any .223 rated can will work but will be overly heavy and large for the application. A .22 rimfire can has to be rated for full-auto fire or you will probably damage it if you get a little heavy on the trigger. In either case, make sure whatever unit you get can be disassembled for cleaning, as an AM180 will fill one up with lead and carbon very quickly. FWIW, Bowers makes one that is rated for "heavy full auto" that is easy to disassemble and clean called the Icon. I have the older and heavier version of it, the USS, and like it. https://bowersgroup.com/icon/

It does seem to be an issue related to the M60 only and yet it goes unresolved even with the latest incarnation of the design (the E6) which incorporated many improvements all through it. One thing that has puzzled me is the use of that strong spring in the bolt that forcibly pivots the bolt into battery as it goes forward. I had a Lewis Gun for a while which incorporated the granddaddy of the M60s gas system and bolt. There was no spring involved and the bolt just cammed into battery as the bolt carrier/gas tube moved forward. No chipped lugs there. Why was that spring added?

Now we need a mag dump video! Merry Christmas, guys.

I am a bit concerned that your new spring might be too long for the stumpy little 51. If you put your bolt carrier on the end of the recoil assembly and push it toward the buttstock, will the back of the BC touch the buffer before your spring goes into coil lock? I think that's the term when your spring is compressed into a solid tube of coils. If that happens, you will quickly beat your spring to death as it will be acting as the buffer. The GI springs are made for a full length recoil rod and a full length bolt carrier, which the 51 doesn't have. You might wind up clipping the spring until the BC can travel all the way back to the buffer without the spring being solidly compressed.

You need to check your bolt gap. The relationship between the trunnion, the rollers and the locking piece governs the amount of energy the bolt has as it travels to the rear. The larger the gap, the more energy the bolt has and your bolt has WAY too much energy. A good strong recoil spring is helpful also, but the key to energy management in an HK system is adjustment of the bolt gap. If you're not familiar with the adjustment and measurement process, go to HKPro.com. There are a lot of tutorials available and very helpful people members who will assist you.

Thanks for the responses guys. I don't know dick about welding, but a buddy of mine has somewhere around 40 or 50 years of experience and he was asking me why they couldn't be welded. He has done some fantastic work in the past, including some that the experts said couldn't be done but I thought I could get some good feedback here. I'll pass along the general consensus.

Has anyone ever had any luck welding up chipped locking lugs on M60 bolts?

Do you know what manufacturer made your drum? If it's one of the modern Taiwanese drums, it's almost guaranteed to work, as they are very well made. Original (WW II or earlier) are also very good, assuming they haven't been abused over their lifetimes. The drums made by Numrich Arms and Kahr can have problems. If you need more info on Thompson related stuff, I suggest you go over to the Thompson Board on Machinegunboards.com. Some of the guys there are incredibly knowledgeable on Tommies and they have a lot of info right on the board.

Yes, you need at least one round up in the feed lips to keep one of the "arms" from passing by it. Then you can put tension on the spring. Don't do more than two or three clicks, as the only way to release the tension is to remove the round and let the rotor spin. Two or three clicks will be the equivalent of what's left over after you have emptied the drum by pulling the trigger and do no harm. More clicks=more energy and you might break the spring.

Wouldn't that be the correct orientation for an HK21 or 21E?

One thing to check on the MP-40 is the locking slot on the underside of the upper receiver. The takedown button pushes a tab up into it to lock the upper and lower receivers together when the gun is assembled and if the slot gets worn and oversized, the upper receiver can pivot slightly on the lower as you are firing. This causes the sear to bind in it's slot in the upper receiver and it can't move up to engage the bolt when you take pressure off the trigger, causing a runaway. I have seen this once and the takedown latch hole had to be repaired via TIG welding. Once it was nice and snug again, the gun functioned perfectly. You can check for this by assembling the gun without the bolt and recoil spring assembly inserted. Try twisting the upper and lower receivers against each other (gently) while you look inside through the charging handle slot and pull the trigger. If the sear doesn't pop up when it's supposed to, it's binding. HTH

Correct. Registered machine guns can have barrels of any length.

I am fortunate enough to shoot at a range with a concrete pad under the firing line, so my links don't get dropped into sand or grass. I just gather up the used links and stuff more ammo into them so they don't get stretched, tumbled, lubed or otherwise pampered. I load 5.56 by hand so any overly-tight links are evident during the linking process and are discarded. .308 is linked in a plate-type machine, so a visual inspection is all they get. The Shrike (yes, it's that old) and Miss Piggy don't seem to mind. Oh, yeah- I'm running Tula steel cased ammo in the Shrike. It ain't supposed to work but the gun goes bang anyway. Like Ted, this is my personal experience over 40+ years of MG fun and worth exactly what you're paying for it. YMMV

I ran a thousand rounds through my Lewis Gun a few years ago. The initial firing went just fine and the only problem was very short life while being reloaded. After two reloads, the brass started separating at the case head. I found out later that this was known to happen with this vintage brass. If you aren't planning on reloading it, it's OK ammo.

I haven't fooled around with the .300 in a while, but when I did, I used GI aluminum 30-rounders with no problems. This included a lot of powder-coated bullets.

On mine it was on the underside of the tube so you had to field-strip the gun to see it.

My two cents- the rifle has been very well cared for and hasn't been used much, but judging by the dent the dust cover has put in the lower receiver, it's been cycled more than a few times. Also, the grease or cosmoline can't be original, because Colt never used it on the guns they shipped. They relied on "VPI" paper and other high-tech chemicals to keep their guns from rusting so that application of grease was done by someone else. A proper sling should be one of the black cloth ones. FWIW

I agree- Bob is an absolute treasure in the NFA world. May he live a thousand years!

Back in the day when Scott Andrey was producing nice stuff, I had him make me a custom Sterling barrel that was longer than normal and threaded on the end. To install it I had to open up the exit hole in the front of the Sterling just a wee bit and now It's just a matter of screwing on my suppressor whenever I feel the need for a quiet Sterling. Even at today's prices, I don't think a run of extended barrels would be that expensive if someone were to make them.

A small number of examples produced will do it also. I suspect that's the case with the Group BAR because they never made that many of them. The West Hurley M1A1 Thompsons were added to the C&R list due to a small number of them being produced and later on the 1928s were added also even though there were more of them made. The total number was still deemed low enough to make them rare firearms.

I read "Guns Up" many years ago and enjoyed it a lot. I am delighted to hear that Mr. Clark is still around and able to pull the trigger on a "pig" as well as he used to.

FWIW, I measured the threads on my K and they're 1.4" in diameter. The thread pitch is around 16 tpi.

Those aren't MAC threads. An old Mk9 was probably set up for a Smith 76 or Swedish K or it might be set up for an UZI already. It would be some SMG that used an external collar of some sort to hold the barrel in place. It might require a modified barrel to be used. It would be a large project to retrofit one of these cans to a different gun as they were designed to be pretty specific in usage.

Pending receipt of funds, the above MAC is sold. Thanks to all that responded.