Problem using Lafette ...HELP!

[ctbea]

I spent some time at the range today evaluating the MG34.
From a bipod, Mobil1 'd parts and ammo links, 11mm b0oster cone, and using early 70's Romanian lacquered steel cased "light ball", the gun ran very smoothly and reliably.
THEN, I moved it to the lafette. Not so good. Single shot worked well but using dauerfeuer, I experienced frequent stoppages with fouled empty links, light firing pin hits, and failure to feed. I surmised the 11mm booster might not adequately compensate for the added resistance of the lafette upper and maybe the search fire mechanism. I changed the booster to 9.5 then 8.9 with no function improvement . I'm not keen on using the 8.9...ran almost as fast as a 42...not good. I have not found youtubes on lubricating the lafette and cleaning the grease from the Search fire is a no go...I just squirted a bunch of WD40 into it.
Looking for diagnostic help...could the culprit be the 147 gr light ball? My only other ammo is older Yugo '79 and a small amount of Canadian DI '42. I have not pulled the Yugo and Canadian bullets to assess their weight. Will they make a difference?
Otherwise, I'd like to get Mobil 1 into ever sliding part of the lafette. I have yet to find anything helpful in this regard.
Any recommendations, opinions, and ?? are gratefully welcomed.
Thanks, Darryl

[JBaum]

Sounds like the buffer on the lafette is so loose that the gun shakes so bad it absorbs the recoil that the gun needs to run.

YouTube is NOT a source of reliable information.

WD40 is a wonderful product - FOR DISPLACING WATER. It was the inventor's 40th attempt to make a Water Displacing product. Thus the name: WD40.
It is a horrible thing to use as a lubricant, as it dries to the consistency of dried linseed oil. It takes a razor scraper to get it off, and will gum up anything it contacts when it dries. It is NOT a cleaner or lubricant. It IS an excellent Water Displacement product. Spray it on a wet ignition system in your car and it will start immediately. Spray it on a gun and it will make everything stick when it dries.

The gun and lafette didn't need Mobil 1 to run 80 years ago, and it doesn't need it now. Regular petroleum based oil and grease are fine.

[ctbea]

Thanks for the reply...and thanks for your many translations. I have read and re-read D 124/2 many times but its still confusing. Thinking that the tripod could be part of the cause, I'm ordering a pin wrench to dismount the lafette recoil assembly and inspect it.

If your reference to "buffer" was to the gun's buffer, if I put all my weight onto the the buffer assembly, I can feel it move about 1/4" Does not seem "loose" to me, but I have an extra one and will check both for effect.

Re: WD40, my tripod appears to have been bathed in cosmoline. I have found that using WD40, I can thin out the preservative filling the trigger spring, the search fire assembly, enclosed areas of the sled, and other parts of the tripod. The intent is reduce the old heavy preservative's possible restricting effect. I DO NOT use WD40 as a lubricant. Where used for any purpose as a penetrant, its always displaced by REAL oils of some type. I agree the MG34 should not need Mobil 1 but I wanted to diminish the effect of the "light ball" lacquered steel cased ammo in the belts..yes, I was planning to spray the belts with WD40 just before loading.

Thanks again for your attention.
Darryl

[DARIVS ARCHITECTVS]

I am amazed the lafette trolley even moves and all. The lafette should be totally disassembled, cleaned of all gelled cosmoline and residue, properly oiled, and reassembled. You should be able to move the trolley smoothly with only the springs offering resistance. A lafette packed with cosmoline is NOT in working condition. It will gum up the working parts even in small quantities.

The four rollers which suspend the trolley inside the outer shell are mounted on pins which are eccentric cams. The dots on top of the pins tell you what position they are in. The cams are used to adjust the rollers outboard and inboard. The cams should be adjusted so the trolley is not loose and sloppy, nor too tight so the friction slows the trolley. If the trolley is not free to move, the gun itself will not move rearward and operate the search fire mechanism.

When I got my lafette, it was totally disassembled, reprimed and painted, but the search fire unit was packed with original grease from WWII which had hardened into hard wax. Taking the search fire unit apart, removing the old hardened grease, and reassembly is not recommended, but I had not choice, so it was carefully disassembled. There are springs inside which make it hard to reassemble without three hands to placed the internals back into the cylinder, so make sure you take note where all the parts go as you take it apart, and release springs slowly under control to prevent lost parts. Study the parts of the unit while it is apart and learn the function them before reassembly. When reassembling, grease the inner cylinder with a double helix slot for a cam. The interior helical cylinder operates like a ratchet. Every time the gun moves rearward, the inner cylinder is rotated a bit. How much it rotates is set by the defection knob adjustment from 0 to 10. If the ratchet mechanism is gunked up with hard grease or damaged, the ratcheting movement will not work properly. This rotating inner cylinder's double helical slot moves the cam which moved the butt stock of the gun up and down.

John Baum has manuals on the lafette and it's maintenance. BUY THEM, and understand how the parts work, and you will have a good functioning mount.

[JBaum]

If you think WD40 is going to dissolve the storage gunk, you're wrong. The lafette has to recoil freely for the gun to work, but the buffer has to work. Not too tight, not too loose. It's probably adjusted correctly now, it just won't work if you don't have the gunk cleaned off of it. Get a bucket of kerosene and soak the parts in it to remove the gunk. Holding it in front of a space heater to melt the gunk out of it will help, then let it soak in kerosene to get the gunk out of the moving parts. I've seen people take off the front leg pads and get a big tub to soak the whole thing. Take it out after a couple days and use an air gun (or putty knife if necessary) on it, then repeat until clean. Then oil it.

We were talking about the lafette, not the gun, so when I said buffer spring, I meant the one in the lafette. I did say "buffer on the lafette", right?

The WD40 doesn't know that you're not using it as a lubricant. If you're using it for any other purpose than designed, it will dry to crap that's harder to remove than the storage grease. The one and only time I used it for that, I had to use a razor scraper to get it off after it dried.

The Yugo armorer's repair manual describes a double boiler with melted preservative that things got dipped into for storing the. It's a great plan, so long as you're not the one who has to do the cleaning. If you take apart the lafette, take a lot of pictures, or you'll end up buying Yugo the repair manual to see how it all goes back together and gets adjusted.