Problems cocking the semi auto mg42

[striker754]

I'm having trouble cocking my SA mg42. Recently got the gun together, and was trying to cock the gun, get everything worked out for a test run next weekend.


When I pull the charging handle back with the spring in, I cannot get the bolt to pass the feed area to strip a round out of the belt. I cut about 7 or so coils off the recoil spring and I still cannot get the bolt to go far enough back.

The third picture shows how far I can pull the CH back with the spring in. The black mark is where the hook on the handle ends up when I pull the CH back with no spring in.

The second picture shows how far back the bolt goes with the spring in.

The bolt DOES go back far enough, without the recoil spring, to activate the ejector. first pic shows this

I've cleaned out the area on the side/bottom of the gun where the charging handle slides to try to free it up some. Done it to the point of getting holes in the ratchet plate.

Anyone have any ideas? The gun is completely dry, but I dont think oil would help in this situation. I think oil would only make it smoother. What should I do?


The bolt also gets stuck on the FCG when it goes over it to the back of the gun. If it is hit hard enough it doesnt affect it, so I dont think it will be a big deal when the gun is firing.

[striker754]

Well after some searching here and looking at the gun, I need to modify the charging handle because it catches on the hammer right at the black mark.

Hopefully this will fix my problem. My recoil spring has 18.5 coils not counting the brazed ones at the end.

[TOM R]

keep in mind you need the buffer latch installed to kep the buffer straight , if the buffer twists it will block the chargin handle slot and you will not be able to cock the gun, took me a while to figure that one out, also when the bolt is forward the link above it should be empty, if the bolt is forward and a round is above it the bolt will not recoil, just thought I would mention these things so you aren't pullin out your hair at the range due to somethin simple

[striker754]

I do have the buffer latch installed. I tried to cut more area out of the CH slot, that didnt really help.

I think the problem is the slot. Because with no grip stick or bolt installed, i can still pull the CH back the same amount. If the put the gun on the AA tripod and aim it straight down, I can push up and get the handle far enough, however, once it is past the point where it goes easily, the CH will not go back on its own. Needs a rubber mallet

[drooling idiot]

sounds like the welded area where the CH rides might be a bit high and causing some binding . you should check that , even if its smooth , if its a little high it will cause binding right at that area.

[j.bal]

I had the samething happen to me. And like you I found it was hitting the hammer. Once I trimmed the charging handle to pass the hammer all was well. Good luck

[striker754]

The thing is, I dont have the gripstick installed and I still have problems. It kinda looks like the CH is cocked out towards the outside of the gun when it is coming back. I tried to grind inside the receiver (difficult task) to fix this, but it did not work. I took more material out of the channel on the receiver that the CH slides in. No luck.

I covered everything in silicone spray. That made it easier to pull back, but still no change of the length of pull.

I think the bolt might be binding inside the receiver somewhere too because when I pull the CH as far back as it goes, and I grab the bolt and try to push it the rest of the way, it will not go. The recoil spring is not too long, I cut a few more coils off of it to be sure. It does have more room to compress. If this is the case, there is still a CH problem because without the bolt and spring, it does not go all the way to the back

[striker754]

Interesting. THe spring sometimes catches on the full auto bolt block. I had my brother use a screwdriver through the gripstick port and raise the spring up over the bolt stud and i was able to pull it all the way back. I wonder if the channel in the recouperator will raise the spring up a little bit over the stud.

[j.bal]

Does the bolt slide freely in the receiver? With the recouperator in does the bolt fly in the rails when it is pulled back? If not you may have too widen the receiver. One of my problems was that the bolt would be stiff on the rails. Pirate suggested that I should open or widen the receiver until the bolt was loose enough to slide freely. It worked. The charging handle would stick on the inside of the reciever where the weld was high ( I have an IO 4 cut ). I used a Dremil and a worn down wheel and took of some off until the C/H moved freely also.

[haseo8up]

try some oil, you'll be amazed. I had somewhat similar situation, and oil was my cure.

8up

[striker754]

Does the bolt slide freely in the receiver? With the recouperator in does the bolt fly in the rails when it is pulled back? If not you may have too widen the receiver. One of my problems was that the bolt would be stiff on the rails. Pirate suggested that I should open or widen the receiver until the bolt was loose enough to slide freely. It worked. The charging handle would stick on the inside of the reciever where the weld was high ( I have an IO 4 cut ). I used a Dremil and a worn down wheel and took of some off until the C/H moved freely also.

Will try to install the recouperator tomorrow. any more ideas guys?

[Karbinator]

Stryker,
Maybe it's the spring binding on the buffer--since the bolt slides freely w/out spring.
Try turning the spring, or flipping it around so it rests even against the extension.
I worried much about getting the rear section straight b4 welding since a slight cant in the
rcvr would bind the spring and extension. I hope this isn't your problem.

karb

[j. bergmann]

striker754 did you bevel the nose piece of the buffer, from the looks of your pictures the back of the bolt extension is right at the buffer and may not be able to go into the extension?

[striker754]

Its a yugo buffer and is already beveled, I can try some more though.

gotta work today then ill mess with it this afternoon

any more ideas?

[hcpookie]

OK... I thought I had posted a reply on Thursday, but I guess I didn't.... ???


BEEN THERE, DONE THAT!

Pull the buttstock off, push the bolt assembly backward by hand, and shine a flashlight down there. You should be able to see where it is touching. I had to shave (with a dremel) some metal from the top sides of the SA bolt extension. Polish it up, and try it again. Strip it down - slide the bolt assembly by itself. Put on the buttstock and try again. Put in the recuperator and try again. Put in the CH and try again. Put in the spring and try again. Etc.

If you have any Dykem, put it all over the bolt assembly and cycle it a few times. You'll immediately be able to see where metal rubs metal. Most likely, you need to shave and polish something down to make it more loose. If you do NOT have any Dykem, degrease everything and use a black Sharpie marker. The fat ones work better. DEGREASE FIRST! If you don't degrease, the oil will clog the Sharpie and it won't work any more.


A few ideas...

- The black mark. What is inside that area? The "shim" that keeps the buttstock lock in place may need to be shaved down. You can probably dremel the front edge of that and get it to come back more. I'll guess that without the spring, if you "wiggle" it back, or if you turn it upside down and try to cock it, the behavior is different?

- The sides of the receiver can be bowed inward, squeezing the insides. This isn't a problem until you put that big-ass SA bolt extension in there. I had to shave some off of the top sides of the bolt extension right where the top of the rails would rub it. This may not be noticeable until after you install the recuperator!!!

- Your rails may be twisted upward *ever so slightly* to push the SA bolt "up" into the top of the receiver. Again, shaving the SA bolt carrier will probably fix this.

- The FA block may be too high - I had to polish the front and back sides to make it more rounded on top. The spring still catches on mine just a little, but the roundness makes it just rub off. When the spring compresses, I've noticed that it can "twist" a bit in the space. If it twists just right, it will push the carrier down just enough to make it stick on the block. Again, polishing and rounding should help this. I've also found that I can rotate my spring about 90 degrees, and it solves the problem. Seems that my spring has a bend in it. Something to consider.

- The charging handle definitely needs to be trimmed back, as you already observed. Note ALSO - the "new" SA charging handle stud that you must weld to the bottom of the SA bolt carrier must also clear the FA block *and* the grip housing. That was a real bugger to figure out!

- The bottom edges of the bolt carrier need to be rounded off. The very top of the hammer needs to be rounded off. Both areas that touch each other need to be POLISHED!!!! I can't stress how important that is.

My guess? Your SA bolt extension is touching the rails or that buttstock shim.

[striker754]

wow pookie thanks! im off to try those things!

[striker754]

current progress: recouperator is in. CH catch on the bolt catches on the full auto block. Removing material from that to let it clear. Looks like the recouperator will raise the spring over the FA block

[striker754]

All is almost well! Evereything with the charging handle has been fixed. I might have to grind on the hammer a tad so the CH can clear it, since it is cutting it close on catching the bolt and passing the hammer.

Still have to work out a minor bolt sticking issue in the rear of the gun. The buffer looks slanted a little bit so I dont know if that is the problem or not. Slanted to the CH side.

[propos]

Stryker, I was reading your post again. I too, have a similar problem with my buffer. It looks like it is canted slightly towards the CH. I wonder if this is a common occurance. The bolt extension rubs on that side of the buffer. The rear section of the receiver is welded on straight. It may be that the buffer bolt holding the spring in may be bent. Probably happened when the armorer threw the buffer into the bin from 30ft. away. Who knows? I bet if we saw how these guns were taken apart and stored we'd all be cringing in horror. To those guys, it was just a piece of junk.

[gordie k]

S754, the radis on the inside of the handle somtimes hits on the piece on the bolt for unlock i remove and grint it so it puls into the bolt not away