Mosin Nagant Headspace

[swgunner]

I am curious, Mosin Nagants headspace on the rim, this is because the Russians didn't have the tools to properly machine the chamber, and to keep costs low. It also allows the use of different ammunition, without having to rechamber the rifle (original ammo was lead round nose). So my question is how is head space important if it spaces on the rim. Believe me I know headspace is important which is why I have go/no go gauge for the m2 on my keychain.

 

[briansmithwins]

.303 Brit and .30-30 also headspace off the rim. If the rim is what stops the cartridge from falling into the chamber, that is what sets headspace. BSW

 

[Hoppy590]

this is because the Russians didn't have the tools to properly machine the chamber, and to keep costs low.

are you asking a question or stating a Pseudo fact? if its the latter, no. the X54r was developed at the start of the rise of rimless cartridges and smokeless powder. it was just the "old world" style of round. the brits had .303, the french 8mm Lebel, We Americans had the 30-40 Krag. really only the German Mauser rifles DIDNT use rimmed rounds. it has nothing to do with the Russian/Soviet production capacity

So my question is how is head space important if it spaces on the rim

same reason head space is important on any gun. keep hot gasses from blowing back at you. the rim of the round can only compress so much. the rim of the round is X thick. if the distance from the bolt face to the chambers edge is X+2, the bolt will not pinch the rim between it and the chamber. gasses will escape.

if the distance is X-2 the rim of the round will prevent the bolt from closing, and prevent the lugs from locking

 

[stubbicatt]

Beware that even though headspace is on the rim, a measurement to assure that you can ignite the primer, many of the M-N chambers are quite long, quite generous. You can have split cases where the shoulders blow forward upon obduration, if the chamber is long, or of more generous proportion.

I have noticed this more in the older Russian Hex receivered rifles than in the WW2 vintage examples.

YMMV.

 

[swgunner]

thanks all, you do learn something new everyday