Lee Enfield head space.

[savagefan]

#4 mk1 Given that this rifle headspaces off the rim, how much clearance between the bolt head and cartridge rim is too much?

 

[enfielder]

303 British Headspace

Military Spec SAMMI
Go .064" .064"
No Go .070" .067"
Field .074" None

 

[Unforgiven]

Correct me if I'm wrong, the go and no go, is in relation to the reaming right ? If it's a go, the bolt won't close, and you ream a little more, if it's a no go, then don't do anything else right ?

 

[John Sukey]

Wrong. If it's a go and the bolt won't close, you need a lower number bolt head. (shorter)

Too much is over .074

 

[sunray]

"...to the reaming right..." Nope. Headspace on a No. 4 is adjusted by changing the bolt head and re-testing. Headspace guages don't measure anything though. They only tell you if the headspace is within spec.

 

[Unforgiven]

But this is assuming the chamber has been cut to proper depth right ?

 

[savagefan]

Thanx enfielder and John Sukey.

 

[John Sukey]

If by some chance the machinery had not cut the chamber to the proper depth, the inspectors would NEVER have passed it, since they were ALL test fired.

 

[savagefan]

Just a bit concerned as primers are backing out after firing. That's with brand new Remington core-lokt 180gr ammo. Shoots well though.

 

[smellie]

Howthick are therims on the ammo you are shooting? Headspace on these rifles is fine to think about, but I have seen .303 ammo come from factory cartons, and the stuff has rims that are only .037" thick; this means that each and every round will have .026" of extra space between the back end of the cartridge and the front of the bolt...... .026" MORE than whatever the headspace actually is.

You need to know rim thickness!

Another point: sometimes casings will back against the boltface and allow the primer to protrude slightly, especially with low-pressure loadings.

Gauge your unfired versus fired casings.

Have fun.

 

[smellie]

Military spec on the ammunition called for a minimum headspace on the rifle of .064" and a maximum on the rifle of .074", along with a maximum rim thickness on the cartridge of .063". The closer your ammo is to that .063", the less problems you will find.

Rimmed cartridges are famous for what you can "get away with". If the extractor holds the cartridge and the bolt closes, you can get away with a lot. Biggest problem with Lee-type rifles is the bolt compressibility/action stretch condition during firing. You can keep this to a minimum through judicious handloading.

Have fun, always!

 

[sunray]

"...primers are backing out..." That'd be one of the indicators of excessive headspace. Quit shooting it until you've had the headspace checked.