TNW SA MG34 Failure to feed

[deminn]

New to the board, checked out the stickies and relevant posts from the past but still not able to diagnose problem.

A year or more back I bought a used TNW SA MG34 on Gunbroker. Nice, good price, the guy indicated it worked well. When it arrived it was selectively gooped with what looked like a white, lithium based automotive grease and clearly hand been in place for a while and it had not been fired in some time. I cleaned it and put it away to get out this spring and try to shoot.

First problem was a mainspring that was so weak it wouldn't strip ctgs from the belt. Corrected with new spring, that issue isn't a problem.

The problem I'm having is that I can't get a ctg to feed initially by pulling back on the charging handle. The case passes through what I'll call the feed try (don't have the terminology down) but gets bound at the 12 o'clock position on the bolt locking cam/receiver roof. When I open the cover I'm looking at the case head tightly up beneath the feed try held in place by what I'm assuming is the extractor.

I don't see any wear on any of the feed parts, the blue or plum is pristine. So that's telling me it hasn't been used much if at all and doesn't have a history of binding which either could be the ammo being finicky, or the seller might have been somewhat less than honest with me and it's just never been fired because it's not functioning.

Since this firearm is new to me, I honestly don't know if it's every functioned properly, and the issue didn't seem to be addressed here in previous failure to feed posts. I'm using Turkish ammo from 49 which fires very nicely when loaded one at a time dropping them into the breach and allowing the bolt to slam home. I've got a very expensive single shot at the moment.

Any advise would be appreciated. Thanks.

[JBaum]

1. If you put the belted cartridge into the middle of the feed tray with the bolt forward, close the feed tray, and then pull the charging handle back, of course it doesn't feed. That's not the way to load the gun. The bolt should be rearward when the belt is laid in and the top cover gets closed. Then you let the bolt go forward.
As a semi-auto, the gun now fires from a closed bolt, but it wasn't designed to do that. It was designed to fire from an open bolt, and to be loaded from an open (rearward) bolt, so the belt feed is made that way. If the bolt is forward when you put the belt in and close the cover, it's trying to advance the belt when it can't because the cartridge is against the stop in the feed tray. It wedges everything, and the bolt can't strip the cartridge. I'm guessing you didn't get or read the directions for using this semi auto gun? (Not trying to be a smart a$$, but this isn't an AK or AR or like anything else you probably have experience with.)

2. The gun shouldn't fire when a cartridge is dropped into the chamber and the bolt is allowed to "slam home", unless you then have to pull the trigger to make it fire, which is not what you said.

Reply in great detail, where the bolt is positioned when you put in the belt, and each little step in the process.

[deminn]

My apologies for imprecise word selection.

First, extractor is on the bottom of the bolt so I was referring to the piece on the other side of the bolt head.

Second, I get it, no offense taken. I do have another one of these which runs fine and I do understand how they operate.

So I pull the bolt rearward and lock it in the rearward position with the safety. Open cover, place ctg fully over the opening to the bottom, make sure the "inside top part" that shifts back and forth to cycle new rounds in is all the way over to the right, and shut cover making sure it's snapped in. This holds the belt in place. Then I pull the charging handle all the way rearward, flip the safety off and let it "slam home" while my left hand is supporting the belt giving it free play into the mechanism. I see the belt advance as the round is stripped and it starts into the breach. Everything looks fine from the outside until I Pull on the trigger which does not move because the action is not fully closed,. I pen cover, remove belt and flip up feed tray, and there's the ctg head at 12 o'clock being held by the bolt face.

2. What I mean was once the above happens, I removed the ctg, dropped it directly into the chamber, let the bolt fly home to a closed position, then pulled the trigger which fired every time. Not a slam fire situation. I didn't say that well at all.

Thanks very much for your thoughts here. I do appreciate it.

[JBaum]

First thing I'd do is swap the feed tray with your other gun. It sounds like the cartridge isn't being guided ("aimed at") the chamber properly. It's my guess that will solve that problem. If it doesn't, swap the top cover.

[deminn]

Thanks. I'll give it a shot.

[bbrown]

I load a belt into my S/A TNW MG34 and Wiselite Mg42 as follows:

- with bolt closed and topcover open, lay a belt onto the feed tray with the the first round to the left of the feed slot, i.e., the slot does not have a round above it.

- close and latch the top cover.

- manually cycle the action, which advances the belt and feeds a round into the chamber. You may have to cycle it twice; ensure that the belt advances.

- pull the trigger; the gun should fire, advance the belt and feed the next round into the chamber, again being ready to fire.

After an initial breakin period (getting the cycling surfaces to wear together) the guns should function well.

[hakentt]

The OP is clueless on how the TNW SA MG34 loads up initially. TNW only provided printed version of their user manual, I assume OP did not get that when he bought his second hand

TNW MG34 "semi-auto" charging sequence:
*Lock the bolt back. I use a plastic spacer in the ejection port to hold the bolt open.
*Lay in the belt in the feedway.
*Close the feed cover.
*Pull back on the charging handle a little.
The spacer will fall out. Let go of the charging handle. The gun will chamber the first round in the belt.

[deminn]

The OP knows exactly how to load the SA MG34 initially and does it exactly as you describe other than the spacer nonsense. It' s worked regularly in his other SA 34, just not this one.

This one seems to have a issue with the loading tray aperture, receiver edge, or top barrel locking piece not directing the ctg base low enough to not get hung up on the case head ring at the edge of the receiver. I'm going to try switching out the feed tray, then top cover as suggested by helpful posters and see if that works.

If it doesn't I'm going to try a copper spacer/guide to reduce the height of the aperture between the loader tray and the receiver to direct the ctg away from the receiver aperture base. If that doesn't work I may just contact TNW and see what they'll charge me to have a look at it and figure out why their receiver is grabbing my ctgs.

I may not say things in a way you understand, which is my fault. But you don't know what you're talking about concerning the OPs clues. Thanks for your useful assistance.

[JBaum]

I've seen the feed tray cause this problem before, that's why I suggested you swap it.

Hakentt needs to learn to be nice, or go away.

[hakentt]

I've seen the feed tray cause this problem before, that's why I suggested you swap it.

Hakentt needs to learn to be nice, or go away.

Really? We are the only two people that are left on this forum.
Do you have any .308 barrels for sale?

[deminn]

Tired switching out both tray and top cover. Exact same hang up result occurred. I had crafted a thin piece or copper to fit in-between the rear receiver face and the front face of the loading tray to reduce the height and diameter of the opening on the front of the feed tray, hoping to direct the ctg down earlier and change the trajectory into the chamber. This resulted in the CTG hanging up halfway into the chamber.

This is making me think the ctg is entering too low rather than high for a straight trajectory into the chamber.

I'm worried I might bugger up the receiver or tray if I started taking metal off hoping for a higher entry point.

I'm thinking my best option, since we don't have gunsmiths locally I feel comfortable understand working on one of these since it probably never comes up for them, is to contact TNW and see if they'll run some tests on it and correct whatever the problem is they find. Does that sound reasonable to people here who've actually built these firearms or at least have more experience with them than I do?

Comments welcomed.

[JBaum]

Sounds reasonable to me.

[deminn]

Problem solved. Getting everything ready and checked over once more for a preliminary tech call to TNW I found my barrel cone nut unscrewed three clicks too loose. That's all it took to re-align the chamber and now I believe it should be perfect.

I should have double checked this before, but I guess I thought I had several times when I cleaned it last after a single shot experience.

Pro tip: Make sure the nut is tightly screwed in.

Thanks for the help and comments everyone.