Shoulder bump / headspace question

[Bindi2]

Too bad you fellas don’t have a flavored coffee to share .

I drink scotch and use 303s.

 

[Uncle Ed]

Too bad you fellas don’t have a flavored coffee to share .

Sharing a cup of coffee is better than sucking on lemons and writing bitter posts.

My apologies, for running into a Australian I haven't heard from in years.

 

[Coyotefurharvester]

Uncle Ed I tried the spent primer method on my new custom reamer chambered 22-250(2). Showed exactly 0.002 headspace which matched the go,no go measurements the gunsmith provided for each rifle. Going to try it on a buddies 7mms rem mag when we set it up for an elk hunt.

 

[Uncle Ed]

Uncle Ed I tried the spent primer method on my new custom reamer chambered 22-250(2). Showed exactly 0.002 headspace which matched the go,no go measurements the gunsmith provided for each rifle. Going to try it on a buddies 7mms rem mag when we set it up for an elk hunt.

At lower chamber pressures like in a workup load or reduced loads the primers always protrude from the base of the case. This is because the chamber pressure is not high enough to make the case stretch to meet the bolt face. My 30-30 always has the primers protruding at 38,000 cup or 42,000 psi max chamber pressure.

P.O. Ackley did a experiment with a 30-30 Imp and removed the locking bolt from the Winchester 94 30-30 and remotely fired the rifle. Nothing happened because the cartridge gripped the chamber walls and the base of the case did not stretch to meet the bolt face. Meaning no bolt thrust load on the bolt face and why you do not want any oil or grease in the chamber before firing.

I think of the spent primer method as the cheap bastards headspace gauge. I collected old milsurp rifles and didn't want to buy headspace gauges for all these old rifles so I used the primer method to find out how much head clearance each rifle had. And on a rimmed cases if you add the rim thickness to your head clearance you will have your actual chamber headspace.

 

[Webster]

Novice reloader...

Virgin adg brass was .012 - .014 less than saami (zero) using the RCBS precision mic guage.

After fire forming at a minimum charge (seating depth test, mainly to fire form), case grew .007 and now measured .006-.007 under the zero on the saami headspace guage...assuming zero is saami minimum on that precision mic headspace guage, they have not expanded out even to min saami specs yet?

Assuming these may not be compeltely fire formed based off the light charge. Should I just load them up and shoot them again or take that .007 less than saami and bump it back .001 and maintain that headspace?

They empty cases still chamber fine in a stripped bolt.

Your cases don't have to conform to SAAMI specs. They fit your chamber.

 

[Vandy321]

Your cases don't have to conform to SAAMI specs. They fit your chamber.

Understood, was just using saami #s as a reference on that gauge for how much my brass grew during fire forming

 

[Vandy321]

I'm getting about .004 averwge over 10 cases with the headspace measurement using a spent primer. Trice fired brass...does it have more to grow? Brass chambers fine, no need to bump yet.

Does a belted mag take 3-4 firings to fireform?

Would it be beneficial for my notes to get the reamers deminsions from the smith?