Mg42 does not cycle 8mm but cycles 7.62 (conversion)

[JBaum]

Bolt installed in gun, cocked and safed. Muzzle booster off. Things are good when "the barrel bushing pushes in with no noticeable resistance and the barrel returns briskly and without resistance to its extended position..." Page 55, HDv 216/6.

[42rocker]

John just quoted from one of the WW2 books that he translated from original German into English and sells. One of the books that about every MG42 owner should have, my thoughts that is.

Later 42rocker

[Blanksguy]

......also remember that those "Pogo-Test" directions were for a full-auto. MG42 and not the SA42.

For the SA42, the bolt and recoil-spring will have to be removed unless you have a "Bolt-Hold-Open" devise built into the SA42.

Regards, RichardS
US Army, Retired

[Der Alder]

......also remember that those "Pogo-Test" directions were for a full-auto. MG42 and not the SA42.

For the SA42, the bolt and recoil-spring will have to be removed unless you have a "Bolt-Hold-Open" devise built into the SA42.

Regards, RichardS
US Army, Retired

Good catch.
Important info like that is what I see sometimes left out of many of these *semi-auto* conversations, which in many cases seem to assume everyone here has a full auto, when actually most here are looking for semi-auto clone help.

The full auto versions of these guns are for all intents a different animal than the semi-auto conversions in regards to bolt- (WLA), bolt carrier, firing pin(s) grip stick, ejector and recoil spring in most cases are different...even loading procedures are entirely different in a semi converted gun.

A full auto manual can be helpful in *some areas*, but may be useless to new users in the semi-auto modified areas of these these guns - which is most of the modified internals.

I would suggest new semi auto owners first download the BRP semi auto manual which will give them a better understanding of their highly modified MG42 M53 clones internals, then add the full auto manuals after they reach a basic understanding of how their highly modifed clone works.

http://www.brpguns.com/categories/Semi- ... Semi-Auto/

[Blanksguy]

badsnakeii,
Reviewed your replies.....and it seems as if you have additional "issues" coming up with your SA42 now that were not discussed earlier/at the beginning. Without full information and systematic checking of your SA42, may lead to over looking an issue that if corrected later may lead to an additional problem coming up at that time.

The issue with your loading/feeding only happening about 90% of the time may be from:
1: Incorrectly bent cartridge-depressor in the 8x57mm top-cover not feeding your 7.62x51mm ammo ....... but we have seen 8x57mm top-covers work well for both calibers in some MG42s/SA42s..........but not in every gun (the fixes for this when firing 7.62x51mm are using a 7.62x51mm top-cover and feed-tray..........to check the angle of the cartridge-depressor = order one of JBaum's gauges from his web-page).

2: There are other items to check on your SA42 (MG42) that we could sit here and list everything down to check one-at-a-time........but would be easier for us if you read up on our MG42-Board becoming familiar with the MG42 "system" and possibly ordering some of JBaum's user manuals in English to help understand the MG42 system.
The link to BRPs Semi-Only User's Manual may assist you also.
With this posting......I'm not trying to keep from helping you, but to have you read/learn from all of the information posted on the Board here.......then check out your SA42.......and with a better understanding of how things fit/function on the MG42 and SA42, to go forward to the range and try your weapon out (That.......and that Wise-Lite should have built your SA42 correctly to begin with, or you should return your SA42 to then for their "adjustments".).

Your Barrel-Bearing is not worn out and is only checked if "cone-of-fire" is too large/spread-out on target......or if the keys are broken or the bearing gets stuck in receiver....usually due to excess carbon. Remember that you stated that the front half of the receiver (Barrel-Jacket was original and complete from behind the cam-piece/"Trunion" forward......so everything should be good on the forward section......correct (?).

Remember through this process that you said it fired 7.62x51mm ammo well....possibly only having a few feed-issues (never did say if those were with 8x57mm belts or 7.62x51mm belts-??....and what ammo-??). Most of your "issues" seem to revolve around the "short-stroking" of your recoiling parts during firing of 8x57mm. I, for one, would try some known good recently manufactured 8x57mm ammunition from a known good source to insure that it is not the 8x57mm ammo....and then go on from there checking the condition of the 8x57mm chamber, and for any parts changed and/or incorrectly assembled.

Regards, RichardS
US Army, Retired.

[Blanksguy]

Guys,
This is a good example of information that is needed for us to assist you in correcting any issues you are having with an MG42 and/or SA42........

We need to have you familiar with the system and how the parts/assemblies work/interact with each other.
...but we need a methodical method to you listing down what you have, what you done and/or tried, and what happened when you tried it.

Clear photos can and do make this process a lot easier for both the understanding of the person who owns the MG42/SA42....but for those that are trying to help him/her sort out the issues in a logical manner. Guessing at what is wrong, or guessing at what could be wrong only gets us off of the issue/question at hand.

To assist new owners/builders in this, there are a few manuals in English available by JBaum from his web-page........BRP-Corp's Semi-Only Manual for the SA42.........and as always, basic information contained in "Folke's" book on the MG34 and MG42.

If we can't figure out what the issue is, nor what is being asked......we can't help you.......so the more detailed information from the owner/builder, and all of the problems listed in the first posting, will really help.

Maybe 42rocker can post a sticky in both the MG34 and MG42 Build-Sections as a possible "List" of all information needed by us to help you would help (?).......we could then refer those people with weapon "issues" to it "if" that have not already read the list (?).

Regards, RichardS
US Army, Retired.

[badsnakeii]

Ok. Did the pogo test without bolt and recoil spring installed. If it's supposed to be done with them in you need to clarify that.
-7.62 barrel and bearing pass A+++
-7.62 barrel with 8mm bearing pass but allot weaker return power.
-8mm barrel with 8mm bearing pass...but not even close to the umph the 7.62 one has. There was no binding or hang ups I felt out of 10 cycles.
-8mm with 7.62 bearing pass. I would say this combo has more return power than the 7.62 barrel with 8mm bearing did.

-inspected my bearings. The 7.62 is what I would call surplus A condition. The 8mm however has 2 possibly 3 tabs that appear to have been ground on or have been worn out through use. It falls out with the barrel about 60% of the times I tested that tonight. Furthermore I think the face of that bearing has been turned back. ...maybe this is how the tabs were damaged was by the jaws of a lathe. My guess is someone turned off the extremely eroded face and cold blued it to make it pass as untampered.
-the hole in my 7.62 bearing is 9mm (.357) : Length 49.08mm (1.932) : OD is 28.84mm (1.135) Fits "loose" probable for expansion if both bearing surfaces under FA fire.
-the hole in my 8mm bearing is 8.75mm (.342) : Length 47.26mm (1.856) : OD is 28.75mm (1.130) fit is sloppy and surface is pitted/rough.

[badsnakeii]

Sorry my page must not be reloading the new replies all the time.
I'm not new to the gun build world by any means. I've restricted a dewat (in legal semiautomatic form) Russian ak47 that had the barrel on both ends welded shut, bolt welded shut, fcg welded to itself/inside of receiver/bcg, and had the cover and mag welded in. Also restored countless Mauser 98 rifles and colt 1911 pistols just to throw some out there.... I'm a tool maker precision machinist by trade.

-I'm using belts stamped 90 -T (both 8mm and 7.62 nato fit well.) I have an original pair of German 8mm belts and starters but didn't want to really abuse them.

-some books would be nice and I'll get some. Though I do have a very pricey toy that eats expensive ammo that doesn't help my wallet get fatter. Lol

-I would've sent it back but they didn't seem like they would have time to get to it for awhile and also had little interest. They told me when I sent it to them it was an as is build and that this was still a prototype not yet in production.

-I'm not the fondest of posting pictures of my guns. Call me paranoid. I would love to share but I'm reserved on that I guess...

-it has no problem feeding the first rounds. Just the 8mm is longer than the stroke it's getting so it doesn't eject the case before it gets out of the bottom.

oh can I put a brass catcher on this?
-I reload all my reload be brass. I hate losing it...almost takes the fun out of shooting to loose brass. On that note I have loaded some fairly hot 8mm rounds for this with no improved result in cycling.

Thanks again guys

[42rocker]

On your brass, get a piece of rubber tubing and fit it to the front of your gripstick. Or the ejection will cause the brass to get a bad ding in the side as it will hit the gripstick.
Glad to hear of everything that you have done. Good Luck with this also.

By the way you now have 10 posts. I'm guessing that this gives you more rights on the site. Enjoy the search button and what ever ten posts means.

Later 42rocker

[badsnakeii]

Haha. Ok. Thanks. I already have been. I wasn't trying to be a smart ass. Just put out there I have experience and am not completely inept.
I would agree however these guns are a total different breed. They are fascinating and a pita at the same time. The operating principal is ingenious...granted there's allot to be desired and better designs now but in some way shape or form most modern belt feds incorporate at least 1 design principal of the mg42.

I learned in my rpd build that these guns were designed to be full auto and making them semi is for lack of a better term stupifying. It's quite the undertaking to get one of these to operate in a manner it wasn't designed to. Hence why it's such a chore to load one of these....they were designed to be open bolt.

I greatly appreciate the opinions and help of the members here.
Thank You very much.

[messerschmittfan]

Not sure if this has been covered but one of the big problems I have found with helping people with the semi-auto 42 is the bolt binding in the rails. I always remove the grip stick and leave the top cover off and install a bolt. It should slide all the way to the barrel without any restriction or slowdown. I have found on two Wiselite guns that the bolt slowed down or stopped halfway down the rails due to restrictions that were removed with some filing. Once the bolts slides freely most of the problems have been solved. The other issues with weak hammer springs and the round depressor have been covered as well as the proper loading method. I also alway use a LOT of oil on/in the bolt for the first 100 rounds. Once it is broke it a little dap of grease will do. Harry

[badsnakeii]

My rails were so tight I had to lap the rails in with Diamond lapping compound and a dead blow hammer. This was acording to wiselite normal with the clamshell type receiver.

It slides nicely. What grease do you guys use? I'm using both oil and grease. Grease on the rails oil on the other components. The grease I'm using is high pressure high temp anti wear stuff we have for our shaping machines.

[messerschmittfan]

Sounds like the same grease I am using, high temp that makes your fingers slippery just looking at it. Unlike the MG34 the MG42 should have a lot of free play to work right. Going out to the range right now to try out two MG34's I just tuned. Harry

[badsnakeii]

It's unreal how images of how the shell bag attaches to the receiver are non existent. How does the brass cather/shell bag attach?

So in fitting the top cover and feed tray for the 7.62 kit I determined that the WLA receiver is not welded on center line of the barrel shroud. Kind of remember thinking this before when I was first fitting the bolt. I remember the roller was hitting and binding on the left side of the receiver channel. Also the top cover was hitting the left side also...

yeah...I think I kind of block all the nightmarish problems I had while first going through it.

[Blanksguy]

badsnakeii,
The "non-existent" photos of mounted shell bags are probably due to people (like yourself) that do not want, or are reluctant to, post photos of their guns (?).

Also, photos really are worth more than a thousand words and explain more that you could ever believe for us in helping you.

On you bolt "dragging"........it should not drag at all, but be able to slide the entire length of the receiver.

Regards, RichardS
US Army, Retired

[badsnakeii]

One would think Google search would come up with something on the brass catcher.

I don't appreciate being attacked fyi. Vet or not it's not cool ok. Take a deep breath please.

Obviously I didn't expect it to be normal for it to contact the receiver in the channel or the fit of the top cover to be offset. From what I'd found WLA was the best option to have the build done.

I greatly appreciate the info and advice.
Thanks.

[JBaum]

The shell bag attaches to the ejection port, which may not be the proper length on your wiselite receiver.