View Full Version : Mosin-Nagant headspace

September 7, 2010, 10:31 PM
It seems many Bolt Heads from these old Rifles have been milled or grinded on the back of the bolthead, nearly making it impossible to remove the ejector(which is needed to install the headspace gauge). Does anyone know of another way to measure the headspace on the Mosin-Nagant ?

September 7, 2010, 10:47 PM
Did you already buy your guages?

If not, try these. You don't need to remove the extractor. I bought a set, since it seems that the 7.62x54r cartrige is just so damn loveable that i have a few rifles chambering it now...:D

If you lived closer, i'd envite you try them, but you seem to be on the other coast, and that would be a heck of a drive.


September 7, 2010, 11:43 PM
Thanks for the info. And thanks for the offer,much appreciated. I checked out that Website and I,m going to put in an order now ! Customer is waiting,so this will be a big help!
Good Shooting to you ! Love those Mosin's

September 8, 2010, 03:51 PM
I have these. They work great and don't require extractor removal either.


Jim Watson
September 8, 2010, 09:49 PM
What do you do if you find your MN headspace to be out of spec?

Don P
September 9, 2010, 06:32 AM
What do you do if you find your MN headspace to be out of spec?

Good question.
I'll add, just drop back 10 and punt.

F. Guffey
September 9, 2010, 07:52 AM
Head space? Checking head space? How many ways? I do not know, I do use three different methods/techniques without purchasing an over the counter gage, I prefer all of my methods over the commercial version(s), I check head space in thousands, commercial versions are go, no and beyond.

Off-setting head space on a chamber with a rim, try finding cases with thicker rims, try to determine the length of the chamber from the bolt face to the shoulder of the chamber then learn to measure case length from the head of the case to the shoulder of the case, then the tricky part, adjust the die to prevent shoulder set back, this method is more effective on cases with shoulders, but not as effective as on cases with long tapered bodies like the 303 British, 30/40 Krag, 300 H&H 30/30 etc. It becomes an either/or, head space on the rim or head space on the shoulder, it takes a very good die and chamber to do both (or get both close).

Then there is the set the barrel back or find a way to move the bolt face forward? A friend had .007 head space on an 03 he was building, the problem ? it was a period correct 1911, he had 80 plus bolts, I had 30+, I offered to check all 100+ bolts for the effect each had on head space but even if one was found to reduce head space it would not be period correct and all 100+ bolts could be withing .0015 of each other, and there is no promise another bolt will reduce head space.

F. Guffey

September 10, 2010, 07:45 AM
I check headspace with a tire, some duct tape, and a long piece of string. :cool:
I've never had a problem with a Mosin.

September 10, 2010, 07:53 AM
Chamber a round, point down range and turn your head. If your gun doesn't blow up when you pull the trigger, your good to go!

September 10, 2010, 06:54 PM
What do you do if you find your MN headspace to be out of spec?

Well, there are three guages: Go, No Go, Field. The bolt should close on Go, and not close on No Go. IF it closes on No Go, then you use the Field. If it fails the Field, then you shouldn't use the rifle w/o making repairs.

Repairs could be as simple as finding a new bolt face that makes it work, or having to take the barrel off, machine off some metal and ream a new chamber back to headspace specs. In most cases, you just get a new mosin.

September 11, 2010, 04:25 AM
The way the Mosin is built: a catastrophic pressure excess is much more dangerous than most other bolt action rifles. So, it's ideal to get it checked before using it.

Also, in many cases: it is cheaper to get a new Mosin than getting yours fixed by a gunsmith.

September 11, 2010, 06:40 AM
I never blew a primer with a Russian, but other than that they are built like a tank.

September 15, 2010, 01:54 AM

Thanks for the Link, I purchased the Okie Gauges and they worked fantastic. Took just a few minutes, and Headspacing was complete. (pass).

So, I would definitely recommend these gauges, great to not have to TRY and remove the ejector from these old rifles.