No dice.. Semi Auto MG42 to light primer strikes to fire.

[ncreptile]

Took the MG42 to the range, I am 100% confident I was loading it right, it would chamber a round just fine, it would even eject the round just fine.

But it would not fire a single round. I was using romy 8mm on german ww2 surplus belts. What I first noticed was the firing pin protruding from the bolt face, after 4 rounds of cycling to shoot, this stopped happening and I did not see the firing pin.

I also noticed that unless I assisted the charging handle forward a little, that the bolt would not seat itself and I'd have to open to cover and push it forward a little. Once I started assisting the charging handle forward a quarter of the way it held onto the round and chambered perfectly.

Issue is when I fired, all I got was a click. The rounds have a very light dent on the back of them. To light to set off a round.

The builder of this took it out and shot it over 200 rounds with no issue so I highly doubt its the springs. I am thinking maybe there is gunk in the bolt thats blocking/obstructing the firing pin from being used? My basis on that theory is that I notice the firing pin protruding from the bolt face before.

Any advice or help is welcome. I drove 50 minutes to the range today, used my one free range pass I had and basically sat there an hour having people drool over it while looking like a fool as I tried to go down a list of things it could be. The good thing is it was a beautiful day, nice breeze, made a couple new gun acquaintances and I learned more about the firearm

Help is most welcome!

[42rocker]

First thought that comes to my mind is how far out does the firing pin come out? Next would be what ammo did he use?? Who made the rounds that he shot??

Sorry to hear about the bad range day. At least the other folks seemed to like it. Now to get it running.

Later 42rocker

[ncreptile]

He used Czech 8mm.
I am in the situation where if I cant spend less than .50 a round, I dont want to shoot it. I have stokepiled a bit of Romy 8mm and its all I have. I cannot find the czech stuff he shot ANYWHERE. :/

Any suggestions on other ammo to try? Could a new trigger spring help eleviate this issue? I would love to keep firing the romy(well.. START firing anyways).

Yes its a beautiful gun, I am learning from this. My first steps into the MG world.

Thanks,
Alden

[ncreptile]

Do you think if I replaced the hammer spring with a heavy ar15 spring, that could do the trick?

I want to shoot Romy 8m exclusively through this weapon. The BRP trigger setup is ar15 correct?

Thanks!

[42rocker]

Romy 8mm is one of the top used rounds for this weapon. Lots of folks go out of their way looking for it. It's what I and many other folks use. Now that we know about the ammo 1st thing that comes to mind is like you said. Heavier Wolf spring. One of the first things that I made sure I put in mine before I went to the range. After that think about talking to John (German Manuals) about his firing pin gauge. Checks how far the firing pin sticks out.
1st Heavy Wolf spring
2nd Check how far firing pin comes out.

Later 42rocker

[Der Alder]

Yep, what 42 said.
I would start by checking the FP protrusion. I use Jbaum's gauge which makes it easy http://www.germanmanuals.com/militaria.html

Sounds like the FP may be binding a bit which would cause it to loose power by time it hits the primer. I'd check to make sure it moves freely. You could have as chip in the channel.

I'd install the heavy hammer spring as well.

Check too to see why you are having to forward assist it into battery. Something has the be dragging or the recoil spring may not be seated correctly into the BC. Is this a BRP bolt carrier and recoil spring or converted BC and spring?

As far as ammo there is not a lot of options in 8mm anymore which is why a lot of guys convert to .308. Romy is about as good as it gets in 8mm though.

[ncreptile]

So my nearest range is well over an hour away so I went to a friends house and fired 3 or 4 rounds of .308 blanks.(The german plastic olive drab ones). All fired, all extracted just fine. The primers in these are very slightly raised so it could be chalked up to that. Obviously the gun did not cycle as it did not have the pressure to do so.

I am still waiting to hear from the builder of this one to see if theres already a heavy hammer spring in there.(I am hoping not as I think this could fix the issue).

The only other thing I can think of is maybe the Romanian ammo I was using is a fluke? I have never had this issue with romanian ammo, but it has been sitting in slightly cosmo covered belts in ammo cans for over a year now, however I dont know how that would effect the primer at all being harder?

Thanks again, going to go down the list of things.

[42rocker]

Well firing the blanks was a good thing. I'm thinking that it's one of those two items that we have listed. You can get a Wolf Heavy spring from several places. Think of some other items to order at the same time as s&h might cost more than the spring.

Good Luck and may you have a great range day next time. Romie ammo is good stuff to feed in. I'm betting that the Wolf spring will do it is it does not have one already one. If it does then get John gauge or find the measurement (I'm sure it's on this site someplace) and measure how far your goes out.

Well here in Florida after we got out of Church all we could think about is what a Great day God has Given us. Hope that yours is as nice.

Later 42rocker

[ncreptile]

Yes, I think the beautiful weather is what is keeping me in good spirits.

Will keep y'all updated.

[anjongni]

Well, I looked all your photos of possible loading sequences and didn't like the looks of any....
I'm no expert, but I believe that in the semi-42, you should hold/block the bolt back, THEN load in the belt with the first round against the cartridge stop.
The forward motion of the bolt strips off the first round and begins to chamber it long before the feed lever begins to move up the belt. It's a function of the long straight run of the lever.
Dropping in the belt when the bolt is already forward results in the feed system trying to load two at a time when you cock it, jamming the bolt through the feed roller and stopping the gun.
I hope you get it going....lots of more knowledgeable people than me here....Phil

[Der Alder]

The BRP and Wiselite semi auto manuals each lists a couple of ways of loading.

Loading the semi auto MG42/M53 as per semi-auto manuals:

Method 1 (BRP)-
Loading with the hold back accessory.

Retract the bolt using the cocking handle. Insert the bolt hold back through the ejection port. This will be creating a wedge between the bolt and front of the ejection port. Raise the top cover and place the belt on the feed block, so that the first round is on the feed block slot and the leading tab is to the right. Close the feed cover making certain that the roller on the bolt carrier is aligned with the transport lever on the feed cover. You must pull the cocking handle back, wait for the bolt hold back to fall from the ejection port, then release the cocking handle such that the bolt strips and chamber the first round with significant force.

Method 2 (BRP)-

After the operator has become proficient in the loading the gun, he may keep the feed cover closed while loading. In that case make certain the bolt is fully home, then insert the leading tab into the feed opening on the left side of the gun, and pull it to the right until the three paws on the underside of the feed cover engage the first round. Never allow the bolt to jerk forward without having inserted the barrel because the cocking slide could be damaged.
---------------------------

Wiselite manual-
Loading the firearm

Check belts for broken or bent links. Start loading the belt five links in. Load the rounds so that each round clicks into place. When loading the firearm place the belt across the feed tray. Do not place the first round into the slot of the feed tray. The first round must be placed to the left of the feed groove.

If the first round is placed in the groove, when the top cover is closed the tip of the pressure plate will contact the round and may bend slightly. This will cause the rounds to be misdirected when entering the barrel and may cause malfunction. The pressure plate will then have to be readjusted for correct feed.

When closing the top cover ensure the latch is completely secure.

Cocking:
With the belt loaded in the feed tray and the top cover is securely latched, using the pull tab or first few empty links, pull the belt to the right drawing the first round under the depressor. There should be a noticeable click and the belt will stop being relatively easy to pull. Then pull the cocking handle to the rear and release, loading the first round into the barrel.

For some pulling the cocking handle to the rear with the first round clicked into place proves rather difficult. With some cross arm action, the cocking handle can be pulled and held to the rear with the right hand while the belt is being pulled to the right with the left hand. Once the round clicks in place, the cocking handle is released loading the round into the barrel

[42rocker]

What is of course interesting to me is that the builder stated that he ran 200 rounds without problems before he shipped it.
Now the builder -- """He used Czech 8mm."""

Owner is now having problems running Romie 8mm which according to a lot of folks is some of the best ammo to use and this is when he is having problems with light primer strikes. Interesting.

Later 42rocker

[1851NAVY]

I was having the same problems with mine.

Check the firing pin protrusion. I had some 8mm that the primer seated very deep into the pocket - creating light firing pin strikes.

Check to see that the rear of the bolt is clearing the hammer COMPLETELY. My bolt was barely touching the rear of the hammer - enough to prevent the bolt from moving forward that extra tiny bit (less than 1/6") - creating light firing pin strikes.

Pull the grip assembly and double check the bolt slides freely all the way up into the barrel. If it hangs up at all when you are charging a round it may be enough to prevent the bolt from seating all the way - creating light firing pin strikes.

Check the seating of the specific cartridges in your barrel and note any differences. If case lengths are too short it may create light firing pin strikes.

Check the primer depth of the different rounds you have - if the primers are seated too deep it may cause light firing pin strikes.


Loading - using a belt with a half dozen or so empty links I've been opening the top cover, laying the belt in place (open side down) with an EMPTY link over the feedway opening and a live round in the next link, closing the top cover and charging the gun. When you pull the bolt back the stripper on top of the bolt head passes through the empty link, the feed arms slide the belt over 1 place - so the live round is now centered above the feed tray and when you let go of the handle the bolt strips that round and inserts it into the chamber. It's been working well for me.

It took me almost 3 years to get mine running right. I actually pulled out the first set of rails and scrapped them then I installed a new set with a new fixture I made so everything was perfectly aligned. I had a lot of issues with the bolt not sliding freely - I believe that was the majority of the operating issues I had. I also decided to purchase one of BRPs new semi bolts and grip assemblies - very glad I did. The new designed firing pin is larger in diameter so it takes more pounding and you can use your unmodified bolt head. The grip assembly is beautiful and has an operating safety just like the originals - it also came with a heavy duty spring for those hard primers.


I hope this helped a little - good luck and let us know what the gremlin was.

[marknct]

The late 60's FN tracer that is out there works when Romy won't. If it lights with the FN get out the Dykem and color up the hammer and bottom of the BC.
1851 said something that doesn't get mentioned enough. These things don't work out of the box even if they tested ok by the builder. It can take many trips to the range to find where the Dykem rubbed off THIS TIME. The clearance you made this time lets the new binding spot show up during the next firing session,until you get all of them. There are many.
The firing pin is 2-3 times longer than the AR and goes thru 3 items which can bind it. They all have relatively independent alignments which doesn't help matters. If the CS isn't parallel to the rails as 1851 mentioned that uses up energy. The hammer might hit the ejector if the clearance isn't right. One of my threads has pics i think.
The big spring might help but it won't be reliable until the hammer swings freely and the 3 are aligned .

[anjongni]

Marknct, that was one of the best explanations I've seen of the hurdles facing the semi-auto MG42 fire control system. The long, skinny firing pin passing through three different moving components with different centers is a challenge, then setting it all off with a skinny little AR15 hammer is not always successful.
Illustrates the hurdles the creators of the MG42-semi system faced when converting F/A machine guns to fire one at a time.
Is the system we all use (BRP/Wiselite) the only "officially approved" way to modify the fire control system for semi-operation? Maybe it could be updated/modernized somehow.
The MG34-semi uses a "striker", like a Glock, which seems to work very well....Phil

[marknct]

That might have been one of my more coherent rambles. Guess who just got back with some Romy and freshly dimpled primers? It didn't really sound great when the charging handle was released. Started running the bolt assy. and it felt fine then the charging handle. Really took a lot of effort going in to the stow position. When I pulled the trigger without a round in the chamber and a finger on the BC it seemed to still jump a little or do something. It turned out that the kicker was binding against the receiver during its closing arc. This used up a lot of forward energy and the hammer was probably doing the final tiny bit of BC movement. A few passes with the dremel and it closes effortlessly now. We'll see if that helps the dimples turn in to pops next time. No making fun of the crappy weld.

[marknct]

Only the kicker was ground on for this go around. 100% with FN and 90 % with Romy and it sounded good. It doesn't make sense that the kicker would affect subsequent rounds so I guess it was just a good day. All fired from tripod. The trigger trip needs to be cut down for the BRP pack. Had some more thoughts on the FP that i'll post when I get a chance to play.

[JBaum]

And this is why very few people are willing to build a semi for someone else, especially if the builder has to state the price up front.

[42rocker]

Sounds like you got it to work almost all of the time.

Later 42rocker