Light primer strike/ round not going into battery

[sbude57]

I've completed my SA MG42, and am in the process of testing it. It seems that when I charge a round, it strips the the round from the belt alright, but when I pull the trigger, "click". If I open the feed cover and remove the belt, then manually cycle the action, the round in the chamber does not extract. Yet when I let the bolt slam home, I can fire the round, and it extracts perfectly. I've gone ahead a few times and extracted the round without firing, and upon inspection of the unfired round I can see evidence of a very light primer strike. Needless to say, this really has me baffled. Could someone please point me in a direction to troubleshoot further? I did manage to get off five quick rounds once today, after that nada.

[JBaum]

So, it sounds like the extractor is not closing on the cartridge / the bolt face isn't closing on the barrel. If it did, your cartridge would extract. Try pushing the bolt fully forward by lifting the cover after the bolt goes forward, and pushing on the bolt to see if it's fully forward. Safety on, or maybe use a dummy cartridge - one with the proper weight, not simply a cartridge without powder (sand is a good substitute). However you do it, you don't want to test the hammer with the top cover open and a live cartridge in the chamber.

The SA MG42 is on the edge of not having enough recoil spring force to operate to start with. You may need to find a way to increase the recoil you're getting, or you might find the hammer has been rubbing on the inside of the bolt extension. Sometimes the hammer edges need filed down for clearance so that it doesn't rub there and lose energy. If the bolt isn't 100% forward and locked to the barrel, the firing pin can't go fully forward, so check that it's closing properly.

The bolt gliding in the rails has to be as frictionless as possible. That can involve tweaking the rail alignment or smoothing the hammer/bolt contact area to reduce energy loss. The rails and insides of the belt links may need lubrication. Light grease on the rails, and a pass with an oily rag in the belt link pockets may help. You might need a longer or stronger recoil spring. Mark the inside of the bolt extension with dye and dry fire it several times to see if it rubs anywhere. If so, give it some clearance. It may be a bit of all of these little problems, or it may just be one or two.

[sbude57]

Thanks jbaum. I'm presently roughing it camping, so my resources are limited. Yeah, roughing it with my laptop and portable wifi, lol. I did bring some rudimentary tools, anticipating problems. A friend of my son stopped at the house and picked up the original recoil spring, I'm going to play around with that tomorrow. I'll also try some of your other suggestions. I appreciate it.

[sbude57]

Found the issue with the drag. It's the grip stick, more precisely where the bolt slides across the hammer. Through the process of elimination, had the bolt sliding smoothly with the grip stick installed sans the hammer. Once I replaced the hammer, there's enough drag to effect the rest of the feeding operation. The original spring was too long, and I've got nothing with me to attempt to cut it properly. Read where someone used their welder to cut it and fuse the end of the cut. Guess I'll have to wait to get home to attempt that little experiment. First I'll try to get the SA spring to do the job. Going to need to grind a little off the hammer. Fortunately I've got some extra AR hammers in my junk drawer, just in case I take a little too much off. Oh well,at least I got a few shots off, albeit singles. Kind of like having a really cool looking bolt action. Lol.