MG42SA - Break in period???

[joshk98k]

Hey Guys,

I have not run much ammo through my SA42 but when I do it gets frustrating. It'll work for a about 25 (or less) rounds and then hang up in various ways and then I have to tweak tweak tweak!

Do these things need a "break in" period to get all the surfaces and such worn in?

I use LOTS of BreakFree CLP and run it "wet" as has been suggested to me.

Thanks Guys,
josh

[striker754]

no, you just have to make things fit properly.

[joshk98k]

For what I paid for it I think it SHOULD ALREADY fit properly!

I think I'm going to contact the guy who built it and have a chat. This is pissing me off.

[JBaum]

If the agreement from the builder was to supply a working gun, and it doesn't work, then the builder should fix it.

From your single message above, we had no way of knowing that you didn't build it yourself and were having troubles.

If the builder doesn't solve the problem, and you need help figuring out what's wrong and how to fix it, we're here.

[joshk98k]

Thanks Jbaum. I'll see what I can do. They have been really helpful in the past but I figured it would be working better by now. I'm going to test her out again this Saturday. We will see how it goes. Maybe the warm weather will make a difference (like with my G43). I know I can fix whatever is wrong as long as it doesn't require me to weld or fabricate.

By the way, I am jelous of you guys being able to build these complicated things. I wish i could do it myself. Tools and I don't generally mix well. I can do the basics but after that it gets rough. Basically I am the guy that ends up sawing through the sawhorse AND the board. At least that's what my Grandpa used to tell me. Ha!

[MGW LLC]

Ok 2 things.

1. RUN IT DRY with just grease on the rails.

2. How exactly is it hanging up?

[joshk98k]

OK, I'll try running it dry this weekend.

Setup: BRP MG42SA in 8mm running blanks with a BFA (NOT a 2 piece blank barrel).

One thing it does a lot is (I think) not eject the cartridge. I'll pull the trigger, bang, and the bolt comes back but never ejects the round, so the spent brass gets pushed froward stripping and loading the next round but the bolt doesn't close because the old brass is still there! I end up with a round in the chamber and a spent round with a mashed lip (collar?). I can take a pic this weekend when it happens. I don't think it is a simple as I need a smaller hole in the BFA to produce more back pressure because it does work for a few rounds before it chokes.

This is a concern to me because I don't want the stuck spent case to hit the primer and set off the new round.

I hope this makes sense.



Josh

[Cpt_Kirks]

Blanks are always problematic. You don't get much recoil with a blank.

Have you tried live rounds and if so, what were the results?

[kusojijii]

so is it not extracting at all or is it extracting from the barrel hitting something in the chamber and deflecting back in front of the next round?

[M1 Tanker]

How does it fire with live rounds? I would figure that out first and then try blanks.

[JBaum]

Ahhh, blanks. That explains a lot. I'm sure BRP made the gun to fire live rounds, so by changing it to blanks, you're on your own. There are several ways to make it a blank gun, and there's a wide variation of blanks that may allow the gun to work perfectly with one brand, but not with the next. Making your own blanks will be the only way to have consistency with firing.

It sounds like there isn't enough power to get the ejector button at the back of the bolt to hit the buffer so that the shell will eject. A smaller nozzle hole may solve the problem, but you may have some weak blanks too.

Blanksguy is the one with experience to ask for information and help with this, since this is his specialty.

[propos]

Well, it could be you're losing to much gas pressure and the bolt isn't hitting the ejector button with enough force to eject the cartridge. I have no idea how your blank gun is set up. Is the gun capable of using live ammunition? Or is it a blank firing gun only?
I had a similar problem with my 8mm conversion. Not enough gas pressure with the 14.5mm nozzle installed. Using an 11mm. nozzle and cutting about a 1/2" piece of spring off the recoil spring solved the ejection problem.
Let us know what happens this weekend.

[avman]

I just got my MG53 running and it would shoot 10 round just fine and then there would be a couple of jams. It would go back and forth. It sounds like this is a common issue. I am going to try to run about 200 round through it to see if will "break in"

[ScottD]

Just to chime in on what everybody else has said: Its the blanks. I work on my local American Legion's Garands every month or so, and one of the guys always tells me that one one gun hung up on a round and they get all panicked and such. These weapons were NOT meant to be run on blanks, dont expect them to run perfectly.

I hope you get it to run well. IM still waiting to get mine built and these stories scare me sometimes!

PS- Where do you get blanks?

[joshk98k]

OK, here goes...

so is it not extracting at all or is it extracting from the barrel hitting something in the chamber and deflecting back in front of the next round?

The bolt comes back far enough to clear the belt but holds onto the spent case and then tries to load the spent case AND a fresh one.

How does it fire with live rounds? I would figure that out first and then try blanks.

It worked fine with live rounds at BRP's shop. I have NOT fired live rounds with this one. Yes it is capable of firing live rounds with a switch of the nozzle.

These weapons were NOT meant to be run on blanks, dont expect them to run perfectly

I don't expect perfection. I DO expect consistency since I was told that blanks would be no problem by the builder. I have to take them at their word.

Where do you get blanks?

From Blanksguy

Thanks for all the info guys. I'll get more details this weekend and get back to you all.

The gun was built by BRP less than a year ago. I live 90 minutes from them so I went in person to pick it up. I told them that it's main purpose was for reenacting. They said no problem. When I went to get trained on it at BRP's shop they told me to bring in the blanks I planned to use for the gun. I use 8mm blanks from "Blanksguy" so I know they are good blanks. The guys at BRP set up the gun to fire with those blanks. I know to stick with the same blanks for consistant pressures, etc, etc.

I am really not worried that it is the blanks. I have been using blanksguy's blanks for years with no issues in my G/K43's.
It may be not enough pressure as people have said, since it is not fully ejecting.

What bugs me is that it worked great at BRP's shop and then in the field it crapped out and now I'm having this issue. I know 2 reenactors that have BRP MG42SA's and they run perfectly. Once I figure out exactly what is going on I'll post back an see whats up.

I appreciate all the info guys.

Josh

[pdstout]

The problem may be in the top cover. It may be binding. Sometimes the will have a slight bow in the cover. Take all of the feed paws out an check. If it is bowed, bend it back stright in a vice. That is what I havd to do on one of my Post Sample 42s. It shot live great but would not fire blanks. No matter what type of restriction, it would not run. After the top cover was strightened it ran great. The Top Cover and feed tray must be fitted to the gun.
P. Stout 07FFL/SOT

[M1 Tanker]

I think you don't have enough back pressure to force ejection. You need a smaller opening in your BFA to create more back pressure so the bolt comes back far enough to get the ejector to operate. How many BFAs have you tried?

[dluch]

For what it's worth, it took me 2 years & 3 visits to BRP to get mine running consistently. I was very dissapointed after spening $4K and having an unreliable weapon. Finally it's a flawless weapon, but I have to keep a close eye on it - things break easily on it.

Frankly, I question the reliability of home-shop made weapons that many of the guys here spout out about. It's so easy to build a receiver out of alighnment & you're screwed no matter what you "tweak". This beast is VERY tricky.

Best of luck - don't give up.

[bolex]

Guys, remember this weapon is made from sheet metal stampings and by definition it must be tolerant of slight mis-alignment. Note, I said slight. Yes things must be correct, but the idea that this is a complicated weapon, I do not understand that. Hey, just my 2 cents.

[avman]

Dluch

I felt the same about how the home made shop builds can run so well. I have to say I been working on my home made MG and took it to the range for my first sucessful day. 200+ rounds and the only problem was with FTF due to the lite hammer hits on the primer.