I'm going to try to list everything I worked on in the army. I was trained on the M79/M79A1/M219 7.62x51mm machine guns but never saw one after AIT (Advanced Individual Training). I heard that the Louisiana National Guard was still using them, but no one other than the NG was that I know of.
Here's what I actually did work on.
1. M10 S&W .38 Special revolver.
2. M191A1 .45 ACP pistol.
3. M3 .45 ACP submachine gun.
4. M3A1 .45 ACP submachine gun
5. Winchester Model 1200/1300 12 gauge shotgun.
6. M16A1 5.56x45mm rifle.
7. M203 40mm grenade launcher.
8. M60 7.62x51mm machine gun.
9. M60D 7.62x51mm machine gun.
10. M240 7.62x51mm Machine gun.
11. M2HB .50 BMG machine gun.
12. M85 .50 BMG Machine gun.
13. M29 81mm (3.2") mortar.
14. M125 mortar carrier mount for M29.
15. M30 4.2" (107mm) mortar.
16. M106 mortar carrier mount for M30.
At Fort Polk, I had to borescope and pullover gauge an M109 155mm (6.1") Self Propelled Howitzer once. If you're thinking that a 55,000-84,000 pound weapon doesn't sound like small arms, you're right. It was an artillery repairman's job to do it, not small arms repair, but I was so good at my job, I got the shop organized and eliminated the backlog they used to have. Anytime I was caught up on my job, they'd find someone else's job for me to do. I don't know if it was supposed to be a challenge, finding something I couldn't do, or what the deal was. When I was borescoping the cannon, the transformer on the borescope shorted out. I don't know if I was hit with 120 volts DC or what it was, but it was nothing like 120 volts AC that I used to casually shrug off. Back then I used to leave the power on when I changed light fixtures and stuff. If I shorted something out and I got zapped, that was that, and I tried not to do it again. But this was much different. I got burned on the back of my left hand when the electricity arced several inches from the end of the muzzle brake or the head of the borescope, and my heart stopped beating. It eventually started beating again on its own, and after having an irregular heartbeat for a couple of months it went back to a normal rhythm. Nothing that multiple six-packs of beer daily couldn't fix.
When I told someone, maybe my idiot brother, about it years later they asked how I knew my heart quit beating. When your heart stops,
you know it. Believe me or not, but you
know. Normally I'm not aware of my heartbeat. I'm so used to it beating all the time that I don't hear it unless I listen very closely, or it's beating hard. But when your heart
stops beating, it's a kind of silence the likes of which you've never heard before. At least that's how it was for me. I don't hear it much anymore, but when I stepped into the "soundproof" booth at work to get my hearing checked, the sound of blood rushing through my head was
really loud. Now my ears ring almost constantly and I don't hear my heartbeat very often.
I helped my friend replace an elevation cylinder on an M109 howitzer once too. Again, not my job, but he was the only artillery repairman we had, and I had a bunch of guys working for me. Like most things in the army I didn't want to do it was "good training", and it didn't do any good to complain. I watched the guys changing barrels on tanks before but didn't help much. I think I helped unscrew a stubborn barrel once, but most of the time I was busy doing my own job. It takes a BIG wrench to do that, but the barrel has interrupted threads and only has to turn 90 degrees. I think the barrels were 1,360 pounds but I'm not sure. It takes a wrecker or a crane to lift them. Sarge knows how much the M68 gun barrels weigh, and he knows down to the thousandth of an inch what 105mm is. I only know that it's 4.1 something. It seems like I'm forgetting something. The other 2 guys I worked with in Germany fixed a broken latch on the front of an M202A1 FLASH that was used for training, while I fixed several other weapons. When I wasn't doing my regular job I was maintaining my rifle or gas mask, or doing some kind of training. Our Captain in Germany used to love training. But the Colonel didn't like it so much when a bunch of tanks and stuff weren't being fixed, and he put an end to the excessive waste of time we spent training. Most of the time we didn't even do PT, we just went to work after morning formation instead because we didn't have much time for anything other than work.
https://en.wikipedia.org/wiki/M109_howitzer