View Full Version : how to headspace MG42?

08-09-2010, 06:47 PM
I was thinking about turning down a chrome lined 8mm barrel for the mg42 but how do you headspace the barrels?

08-09-2010, 07:01 PM
Kevin the headspacing on these is actually done with the barrel...

its that flat part of the barrel that has a little lip on it..

you'll hear lots of people talking about the rollers and you may be able to get different ones.

but just changing out the barrels changes my headspace on mine and you work it from there.

im using 2 barrels right now and switch them out pretty often if they get hot and i had the one turned on that lip down to match the other one and that made my headspace exactly the same on them both.

got several FA friends that use MG42's all the time and they all have "boxes full of barrels" and will just grab one that the go/no go gauge works with and go from there.

if you dont have a go/no go gauge, you could always make up some dummy rounds and do the "tape" method.

8mm is hot stuff, but once my barrels were matched up ive never had an issue with any brand of ammo.... the tolerances in this gun were just not that tight.


08-09-2010, 07:13 PM
i bought several cheap ones but they are pretty pitted, i never checked the headspace and nothing went wrong. how do you know how far to screw on the extension piece or whatever its called? for the cost of a the best barrels out there for sale (i only know of used ones in g-vg condition) i could get a chromed 8mm barrel to turn down and then put the extension part on it and still be money ahead and have a new barrel thats chromed

08-09-2010, 07:30 PM
Wait... Doesn't an MG42 fire from the open-bolt position? Would that nullify bolt-spacing, or at least make it less of an issue? Seriously... I'm kind of interested in the answer to that.

M1 Tanker
08-09-2010, 07:54 PM
The Germans issued a A,B and C barrel with their MGs that were all headspaced to that gun. You would need to tighten the barrel in the trunnion to tighten headspace. I'm not I would bother. I have 2 semi auto bolts and between them all my barrels headspace.

Headspace matters :)

08-09-2010, 08:34 PM
There is a thread on this on MG42.us. Ill look for it later and post a link

Here ya go

08-09-2010, 10:25 PM
thanks, i will have to check all my barrels now

08-10-2010, 06:14 AM
LMAO FLemgunner is one of those FA mg42 guys.... :-)

MG42 is not really an open bolt.. it has the rollers that "come around" and lock into place... but then again it doesnt actually "lock" solid either.

the barrel goes into the holder and bottom out towards the front against that.

at the rear the recuperator holds some pressure up against it when the bolt isnt in battery.

the flashider and gas booster and muzzlenut all just get tightened down till they bottom out and have a notch that matches up for the retainer (thats attached to the site) or at least thats how i was taught to do it.