Lite firing pin strikes

[flemgunner]

Ok so Im kinda stumped here. Im getting sporadic lite firing pin strikes with romy surplus ammo. The gun is a F/A post sample, recuperator checks good, recoil spring has a good length on it, bolt travels freely, headspace and everything else checks good on it. Any ideas?

[JBaum]

Did you check the length of the firing pin? Sorry, I have to ask the obvious first

[flemgunner]

No prob man. Yep checked the pin. In fact swapped it out for a new one

[gordie k]

some times the bolt wedg will cause this dosent seat to the same place each time it lockes up

[flemgunner]

What would be the fix for this?

[Blanksguy]

flemgunner,

Was that all that you checked before/after a "Post-86" FA build prior to going to the range (?).

I have a lot of ideas on what you should be checking and/or swaping-out........but would rather let you do the typing of the "list", prior to me typing my list and you just answering "yep-checked that.....".
So please, list down everything that you checked....even the obvious items on the gun.

As you are going through your list, think of things that would slow and/or stop the bolt assembly moving forward other than "hard-primer".

Regards, RichardS in MI.
US Army, Retired
Blanksguy2001@chartermi.net

[flemgunner]

I basically went through everything in Jbaums MG42 manual. This has really got me stumped

[Blanksguy]

Well, I guess I have some extra time....so we can do this the one-at-a-time.

I will take it that you have built this FA MG42 Post-86 sample from a WWII German cut receiver (I didn't see that mentioned earlier)....or is this BRP receiver-sections....or "mixed" receiver parts/section of unknown origin (?).

Do the "original-stamped" numbers on both halves of your Trunion/Cam-Section match (?).

Was the receiver welded together, and checked for straightness (?).........
Did the gun ever work for you for more than one shot (?).....was this something that started slow and got worst quickly (?).

When you checked all moving-parts ( bolt, barrel, barrel-bearing, etc.) without the recoil-spring installed......does anything bind or hit anywhere during full movement (?)....especially check at that last section where the bolt is near completion of forward movement.

What is the condition of your Barrel-Extension and Bolt Locking-rollers (?).
Have you check "Head-Space"....as you may have a barrel-assembly with mismatched parts that was just screwed together from recently imported parts.
Have you tried a second bolt-assembly to see if the problem was with the first bolt (?).

When you check the chamber......are there any "issues" with a cartridge trying to fully seat itself.

Any burrs on the extractor where it would open to receive the cartridge (?).

During operation.......this fired from the "Open-Bolt" position.....correct (?).
Have you tried to fire your MG42 without the dust-cover on the ejection-opening (?).
Have you tried a different lot of ammunition to see if it was the ammo ot of specs.. (?).

Does the Barrel-Assembly always go fully-forward to the "stop" that is riveted into the receiver (?).

Does your Top-Cover allow the cartridge depressre to go downward too far, allowing it to drag on the bolt (?).
....and do you have any iussues (parts binding) inside the top-cover (?). Have you checked for binding/dragging with the top-cover open and closed for binding-parts or bent-parts.

Have you check the condition of your belts (?)....any excess binding of cartridges intermittantly (IE: maybe every so often too much tension on one cartridge but not the next few.).

Do you have the Flash-Hider w/Booster-Cup/"Nozzle" tightened down too much where is puches the barrel-bearing (and barrel-assembly) slightly to the rear (?).

What were the results of your "Recouperator-Test" when you did this. If you don't know how, please do a search on our Board and it will bring up how. This may indicate a "challange" inside your recouperator....and did you insure that the forward mounting bolt/nut was oriented in the correct direction during installation (?).

.................several more items to go......but tired of typing.
How about a line-by-line listing of the results of each of the above now flemgunner so that I can gauge your interest in having more information (?).

Regards, RichardS in MI.
US Army, Retired
Blanksguy2001@chartermi.net

[42rocker]

Well that's a nice list. I hope that I stay problem free and don't have to use that list.

I got a Semi Auto bolt with a firing pin that would not push out far enough to make contact with anything. Still thinking about that one, which drill out the bolt wedge or slim down the firing pin to fit..

Later 42rocker

[Bil]

Thanks for your patience and the list,Richard.It should go in the stickies section! ---bil

[Blanksguy]

Bil,
Thanks...."but" that isn't even a partial list of challanges with these guns.

So many people look at a gun and when it doesn't fire, come up with any answer that will (or could possibly) "fit" the challange. There is rarely a complete explanation of what was done to the gun/checked/gauged/etc. during the "build", nor any "pre-fire-checks". Then when something goes wrong or doesn't work......we are given a very, small part/partial information from which we are asked to figure out what is wrong. (IE: Like going to call a "Mechanic" and say "My car won't start.....I turn the key, hear a click sometimes...........what's wrong ??"). Even the German Manuals are really just a "guide"......there are a lot of problems/challanges not covered there because of how our guns were built and to what standards. From what I have seen in the manuals that I have, (and Jbaum can correct me if I am wrong), these are basically "user" level and Company/Battalion/Regimental-level manuals to help solve most problems to keep the guns firing/operational. Not DEPOT-level rebuilding manuals on how to check everything on the gun for wear and/or if gun is operational or not, etc..). Very good manuals, but a higher level manual could be used by some of the "builders" here in the MG42-Board.

I'll wait to see what flemgunner comes back with for his list of each thing he checked from my first-list, and see what he found out so far by each item.
I can go forward after that.

Regards, RichardS in MI.
US Army, Retired
Blanksguy2001@chartermi.net

[Blanksguy]

42rocker,

Send me a detailed explanation of what is going on with your SA42 .... along with some clear photos of the systems parts that you are having "challanges" with, and I can possibly sort it out for you.
I will also need to know how the gun fires with live ammo is this is strickly a "Blank-Firing-Challange"......but if you can't get it to fire live ammo first.....we can start from there.

Please.......give me all of the information in your e-mail first. (E-mail address listed at bottom of page.).
Such as/but not limited to:
manufacturer of gun and ammo.
what ammo belts are you using.
what length barrel-bearing and hole-size in your Booster-Cup/"Nozzle".
what you have tried so far.....what broke......photos of the parts in question (broken and new-parts).
....and last, as always, did you check the guns parts prior to operating it such as/but not limited to Cam-parts-matching, condition of bolt-face, rollers, barrel to include bore/chamber and barel-extension condition.....buffer-shape if it was modified from original configuration.....length of recoil-spring.......caliber of your weapon and was any part(s)/assembly changed before you went to firie in the new caliber, condition and angle of cartridge-depressor in Top-Cover........and last "Recouperator-Test-Results" were_______________________________________________________.

Regards, RichardS in MI.
US Army, Retired
Blanksguy2001@chartermi.net

[flemgunner]

Well lets see
I will take it that you have built this FA MG42 Post-86 sample from a WWII German cut receiver (I didn't see that mentioned earlier)....or is this BRP receiver-sections....or "mixed" receiver parts/section of unknown origin (?).
****It’s a post sample M53 kit built with BRP rear halves. Ive build one from these before.

Do the "original-stamped" numbers on both halves of your Trunion/Cam-Section match (?).
****Trunion is matching

Was the receiver welded together, and checked for straightness (?).........
Did the gun ever work for you for more than one shot (?).....was this something that started slow and got worst quickly (?).
*****Receiver is straight, also no binding anywhere. Gun shoots bursts but gives lite firing pin strikes. No noticeable pattern to it

When you checked all moving-parts ( bolt, barrel, barrel-bearing, etc.) without the recoil-spring installed......does anything bind or hit anywhere during full movement (?)....especially check at that last section where the bolt is near completion of forward movement.
****No binding anywhere

What is the condition of your Barrel-Extension and Bolt Locking-rollers (?).
Have you check "Head-Space"....as you may have a barrel-assembly with mismatched parts that was just screwed together from recently imported parts.
Have you tried a second bolt-assembly to see if the problem was with the first bolt (?).
****2 barrels were headspaced, and also 2 bolts. Does the same with both sets. Barrel extension and bolts were checked and are fine

When you check the chamber......are there any "issues" with a cartridge trying to fully seat itself.
****Chamber was polished before test firing

Any burrs on the extractor where it would open to receive the cartridge (?).
****Extractor is normal


During operation.......this fired from the "Open-Bolt" position.....correct (?).
Have you tried to fire your MG42 without the dust-cover on the ejection-opening (?).
Have you tried a different lot of ammunition to see if it was the ammo ot of specs.. (?).
****Firing was from open bolt but bolt stops forward on the “dud round”

Does the Barrel-Assembly always go fully-forward to the "stop" that is riveted into the receiver (?).
****Yep

Does your Top-Cover allow the cartridge depressre to go downward too far, allowing it to drag on the bolt (?).
....and do you have any iussues (parts binding) inside the top-cover (?). Have you checked for binding/dragging with the top-cover open and closed for binding-parts or bent-parts.

Have you check the condition of your belts (?)....any excess binding of cartridges intermittantly (IE: maybe every so often too much tension on one cartridge but not the next few.).
****I was thinking this as they are new belts but the stoppages don’t happen in the same spot on the belt. Im going to try them in a different gun tomorrow

Do you have the Flash-Hider w/Booster-Cup/"Nozzle" tightened down too much where is puches the barrel-bearing (and barrel-assembly) slightly to the rear (?).
****It is tightened down all the way but I don’t see any “dings” where it may be hitting

What were the results of your "Recouperator-Test" when you did this. If you don't know how, please do a search on our Board and it will bring up how. This may indicate a "challange" inside your recouperator....and did you insure that the forward mounting bolt/nut was oriented in the correct direction during installation (?).
****Pogo test was normal. Forward nut thing “t” shaped is installed correctly

[42rocker]

Blanksguy
Thanks for your offer. Not trying to hijack this topic. But a quick post back on this, hopefully to end it.
Bought "complete" semi auto bolt from a mod (I believe that it was/still is a good Deal) "semi bolt was redo by panaceabeachbum (so I was told, and believe).
Now parts that I checked out (as other parts are not needed at this time, i.e. everything else) bolt head (no bolt body), attached rollers, wedge, and firing pin with spring. When I push (by hand) the firing pin forward, with rollers out in lock up position, the head of the firing pin does not stick out through the bolt head hole. That was stated before, however if I reach over into the spare parts bag and grab a spare "brp, Brian" firing pin and change it out, then push the firing pin (again by hand) the head of the firing pin sticks out through the bolt head an amount that "looks" like it would work just fine, about 1/16 inch more or less, just guessing at this time, did not get the mic out and check it and double check numbers from John's fine line of book's. In a quick eye ball I think that the panaceabeachbum firing pin needs a quick turn on the lathe for just a quick touch to reshape near the tip.
As stated before, I hope that I don't have to use any of your fine list after I complete adding the rest of the stuff to the semi bolt group. Still choosing which parts that I'm going to use on which build...
But trying to check out each part before I add it to a group of parts for a build.

Blanksguy, the optics that I got from you, looks good on my lafette tripod, now to finish mg42 and add it to the lafette to finish the group....

Enjoy life....

flemgunner GOOD LUCK, with this problem which I'm sure that you will overcome.

Later 42rocker