Bolt Carrier ? and trunnion / camming piece ?

[42rocker]

As said, need help with a question on the trunnion or camming piece....
With most of the centerfiresystems kits it seems that the numbers are not matching. Now in the German manuel reprints (Thanks John) they say if replacing, to replace both parts as they were made together and should be replaced together...
Therefore what does everybody think about mismatched trunnion / camming pieces????? For semi auto use..
Ok, as long as they fit nicely?????


Ok, question on the bolt carrier, the bolt carrier was sand cast then machined. However some bolt carrier's have numbers that were made during the sand casting... Like 16 / 01 Are these numbers from the German WW2 time or yugo numbers or???


SOME help if you please.....

Thanks
Later 42rocker

[Dan@AngolaArmory]

Tim,
I'm not sure about using a miss matched camming piece, maybe someone with more knowledge will chime in. If you need a matching one, you know where to look.
On the WWII bolt carriers, most, if not all had the cast in place numbers, IIRC.
Dan

[rocco1911]

I personally have used miss matched ones with no issues but again we are building semis that in no way get the workout a FA gun would get in that area hope this helps...

[www.Prussia.us]

I have built two SA42s, which is nothing compared to guys like Rocco. Both camming piece sets were not matching, BUT they made a nice firm fit. Also as most of the regulars know, the German war-time and Yugo (from what I have handled) never match up if you are trying to mix a Yugo piece with a German one to make a set. The Yugo are more beefy and robust, but of course I used German ones because I am nuts like that

[JBaum]

An MG42 does not have a trunnion, so we're talking about the cam piece here: For semi guns, I wouldn't be afraid of well mated set, regardless of the actual numbers matching, but if a matching set is available for a few bucks more, I'd go with matching just to try to eliminate any possible problem 10 years from now. Either way, there are no guarantees that the matching set will last longer than a mismatched set anyway.

For the rest, I agree with the above.

[Bil]

John,I see you are on your medication again,the 'T' word doesn't have its former effect! Or have you just given up on your effort to educate the masses? And I also agree about the above statements. ---bil

[DARIVS ARCHITECTVS]

John,I see you are on your medication again,the 'T' word doesn't have its former effect! Or have you just given up on your effort to educate the masses? And I also agree about the above statements. ---bil

John must be on sedatives. The "T" word didn't result in him exploding or another 2-1/2 hour bout of projectile vomit.

The visits to the shrink must have paid off handsomely.

[Blanksguy]

I don't believe that the critical issue is the fit of the two pieces of the Camming-piece together.........but in the timing/location of where/when the inner cam-surfaces would lock/unlock the bolt-rollers ( IE: Left vs. right side cam.).

Most should be close enough for an SA42..."but" what would happen on an SA42 if one side unlocked a split second prior to the other when we talk about the pressures from live 8x57mm ammo (??) or 762x51mm/.308 cal live ammo (?).

Just something to think about during your build.
Regards, RichardS in MI.
Blanksguy2001@chartermi.net

[DARIVS ARCHITECTVS]

I don't believe that the critical issue is the fit of the two pieces of the Camming-piece together.........but in the timing/location of where/when the inner cam-surfaces would lock/unlock the bolt-rollers ( IE: Left vs. right side cam.).

Most should be close enough for an SA42..."but" what would happen on an SA42 if one side unlocked a split second prior to the other when we talk about the pressures from live 8x57mm ammo (??) or 762x51mm/.308 cal live ammo (?).

Answer: Excess strain on one roller and also the bolt head. After a while, one of them would break from repeated stress cycling. That's bad, folks. DANGEROUS even.

[Michael J]

An MG42 does not have a trunnion, so we're talking about the cam piece here: For semi guns, I wouldn't be afraid of well mated set, regardless of the actual numbers matching, but if a matching set is available for a few bucks more, I'd go with matching just to try to eliminate any possible problem 10 years from now. Either way, there are no guarantees that the matching set will last longer than a mismatched set anyway.

For the rest, I agree with the above.

I know you can get a good (i'm guessing matching) set from marstar for like $20. That is pretty cheap, if it is possible for you guys to order them, sure seems like a deal to me.

[DARIVS ARCHITECTVS]

An MG42 does not have a trunnion, so we're talking about the cam piece here: For semi guns, I wouldn't be afraid of well mated set, regardless of the actual numbers matching, but if a matching set is available for a few bucks more, I'd go with matching just to try to eliminate any possible problem 10 years from now. Either way, there are no guarantees that the matching set will last longer than a mismatched set anyway.

For the rest, I agree with the above.

I know you can get a good (i'm guessing matching) set from marstar for like $20. That is pretty cheap, if it is possible for you guys to order them, sure seems like a deal to me.

$20.00 Shyeah Right!

[drooling idiot]

a question on the camming piece....
With most of the kits it seems that the numbers are not matching.
Now in the German manual reprints they say if replacing, to replace both parts as they were made together and should be replaced together...
Therefore what does everybody think about mismatched camming pieces?????
OK, For semi auto use.. as long as they fit nicely?????

I edited your quote slightly.

First, I would have to say it would be irresponsible to give a blanket statement that it would be OK to do something contrary to the manual.
Can you get a MG42 style gun to run with a mismatched cam, YES. Is it a super great idea, NO.
If you aren't very very sure about the condition and fitment of the two pieces you should replace them.
Rocco is not your average homebuilder, if hes confident in the combination hes used, I'd shoot those guns.
For any reading this thread I think its a bad idea to roll the dice when factory matched cams are currently available. Click here for link

While its true, a recreational use semi will not get near the work out of full-on military FA, I'm building these guns to pass down the generations. With that in my mind the service lifetime of a SA42 is much longer than a GOV. owned FA. If something were to go wrong the shooters of my guns are much less replaceable to me than the shooters of the GOV.s FAs are to the Gov. So I recognize its important to get good parts on them now and spares for later while they are available.
Please replace any questionable cams, do it "For the children".

[Michael J]

An MG42 does not have a trunnion, so we're talking about the cam piece here: For semi guns, I wouldn't be afraid of well mated set, regardless of the actual numbers matching, but if a matching set is available for a few bucks more, I'd go with matching just to try to eliminate any possible problem 10 years from now. Either way, there are no guarantees that the matching set will last longer than a mismatched set anyway.

For the rest, I agree with the above.

I know you can get a good (i'm guessing matching) set from marstar for like $20. That is pretty cheap, if it is possible for you guys to order them, sure seems like a deal to me.

$20.00 Shyeah Right!

M42-010 CAM $20.00

http://www.marstar.ca/mg42m53p.htm

If there's anyone who needs em, i can order em myself, german matching i'm guessing, as it is not specified that they are anything else. I'm still unsure if John sells MG parts to the civilian market, but i will find out monday if my order goes through for other parts.
Are you guys in America allowed to order MG parts from canada? We are legally allowed to export, so that should not be an issue.

[blackreichswehr]

i'am on the same track with drooling idiot, this isthe heart and brains of this invention--without functional reliability its useless

[www.Prussia.us]

Michael,

Please do check with John, the last time I tried to get a matching German set at first I was told "fine," then I was told "no-can-do," because all they had were a few German half pieces "in the drawer" and then with a form 6 they would send it down to the states. There should be no need for a form 6 for a cam piece or set for that matter.

Maybe he has found and imported more????:D