www.MG42.us

I own a TNW semi-auto MG34. Having shot that gun I was giving it a good cleaning. After taking off the flash hider I separated the "booster cone" and gave it a good cleaning. Reflecting on the gas pressures and heat that are acting on this part I was amazed that it cleaned up so well (still nice and shiny and smooth). I was curious to know more about the "booster Cone" and so I grabbed my copy of the Folke Myrvang book on German machine guns. He described that the "booster cone" should have an 11MM hole in it, but rarely you may encounter one with a 9.5MM hole. The 9.5MM version is only to be used with an aluminum cored 8X57MM training round. The smaller hole makes the MG34 action too "violent" in operation when used with "service" 8X57MM ammo. This causes undue stress on the moving parts.
Guess what size hole is in my "booster cone"? Now I know why this gun really throws empty brass out so hard!
Anyone with a TNW semi MG34, or has a live MG34, or has built a semi-MG34, or has a parts set thinking of building one, I STRONGLY suggest that you check the hole in the "booster cone" with a micrometer. I will be replacing mine before I shoot it again!

good to know.

Is it possible that this is the same size booster hole that is used with .308? Brian at BRP sells the .308 conversion kits. He would probably know.

I don't think I have ever seen anyone offer a .308 conversion for the MG34. Are you sure you are not thinking about MG42/M53's converted to .308?

Ohio Ordnance used to sell .308 caliber MG34 barrels.

BELTLEAD wrote:Ohio Ordnance used to sell .308 caliber MG34 barrels.

Did Israel use .308 in the 34' ?

thank you very much for the heads up. I just went down to check the cone and its a 9.5mm hole!

Opakanopa wrote:thank you very much for the heads up. I just went down to check the cone and its a 9.5mm hole!

Is your gun a TNW also? Interesting that another "booster cone" with an undersized exit has turned up so soon. Fot the folks who have Folke Myrvang's book the information I refer to is on page 89.

My TNW came w/a 9.5mm cone, replaced it with an 11mm - runs smoother - ejected shells fall alomost staright down rather than shoot out to the front.

On my '42, replaced the 11mm with 14mm - it functiona barely enuff to cycle - it's EZ on the parts.

dluch wrote:My TNW came w/a 9.5mm cone, replaced it with an 11mm - runs smoother - ejected shells fall alomost staright down rather than shoot out to the front.

On my '42, replaced the 11mm with 14mm - it functiona barely enuff to cycle - it's EZ on the parts.

I contacted TNW about this situation when I first noted to exit hole size. So far I have heard nothing back. I now wonder if they used this size part on purpose?
Where did you find a "booster cone" with a 11mm exit hole?

Try http://www.mg34.com
I think I got mine from there - or simply drill out what you have (it's VERY hard steel tho)

I actually bought my parts kit from http://www.mg34.com (AA)


I think im just going to drill out my current one to 11mm. Unless there is a market for these "rare" trainer cones.

My rifle was built the first year offered, 2002. Mine also had the 9.5mm cone, I let Tim Bero (TNW's owner) know RIGHT away that it was incorrect. The rifle was beating me up. Bored out to 11.5, it became pleasant to shoot, except for the trigger pull. For my review of the rifle see Small Arms Review (SAR) March 2003, the infamous Shrike issue avaiable through Long Mountian Outfitters.
FWIW,
Dan

I have to wonder if the MG34 parts sets that TNW bought were being used as training guns prior to de-mil? That would explain why they have so many of these "booster cones" with the smaller exit diameters.
I would hate to modify the original part so I will need to track down a replacement.

I just dug out the MG34 parts set I had stowed away some time ago. I took off the flashhider and discovered a "booster cone" that was quite filthy and had lumps of brass stuck all inside it. It does NOT seem to be of the same quality as the one I took out of my TNW MG34. I just measured the exit hole and discovered it isn't even 9MM across! My Luck! No markings on this part ( the one from the TNW gun is numbered). I suspect it to be Yugoslavian manufactured. That entire MG34 parts set has lots of Yugo markings and a new Yugo barrel. An interesting carving is to be found on the side of the buttstock. It says "CRO-ARMY".
So, I will have to keep looking for a "booster cone" with the correct diameter I need.

The MG34 was made at the BRYNO factury in Czechoslovakia during WW2 for the German occupiers.Israel contracted BRYNO during post-war years to make spare parts for MG34's that the U.S. captured and gave to the Israelis after WW2,when they established their country in 1948.That is why a lot of MG34's imported into the U.S. are I.D.F.(Israeli Defense Forse) surplus with the Czech re-designed post-war adjustable leg bipods that the Israelis requested.

That import is done and gone. I haven't seen any of the Israeli (w/ adj zb type bipod) sold for eons.

Sportsman's Guide was selling them until a few months ago.Tom R bought one.

I e-mailed TNW last week and I got an replay back to day:

"HI,

WE HAVE NO AWNSER FOR YOUR QUESTION, SORRY

KELLY"

So I think that they dont even know that there are two type cones!

The smaller diameter cone gives the gun more recoil. It also puts more stress on the bolt rollers, buttress threads, unlocking cams and the ejector and ejector plate. It is a quick fix for guns that do not run right and also a lazy way to get all your guns to work...just like TNW does. It is best to use the gun with the largest diameter hole you can get away with and still have the gun cycle.