jr_roosa
Member
I discovered something shocking while demonstrating some things to a friend about headspace and gas guns. Apparently what I found is nothing new, but I can't believe that I never saw this anywhere in the years that I have been reloading for my rifle.
I have a series of sized brass that is about 0.001" or 0.002" shorter than the next that I used to measure my chambers to set up my sizing die for my Garands, which conveniently are within about 0.001" of each other...close enough for government work.
Anyway, I size brass to about 0.002" shorter than the longest case that will allow the bolt to close (stripped bolt without ejector). Up until this point all is right with the world.
I show him how fired brass won't fit back in the chamber, how commercial brass will fit without any trouble, how properly sized reloads fit just fine...and then I put in some HXP:
Untitled by jr_roosa, on Flickr
And the bolt barely starts to close!!!
I post this on the CMP Garand forum, and it seems to be old news that HXP runs a little long, but the Garand just smooshes it into the chamber without slamfires, out-of-battery discharges, or any small animals being harmed.
Then, they point to Hatcher's Notebook where it shows that GI .30-06 is supposed to be up to 0.006" LONGER in the shoulder than a Garand chamber, and that some machine guns back in the day had a chamber 0.011" short to MAKE SURE THEY SET THE SHOULDERS BACK ON CHAMBERING to prevent case head separation!
So...this begs the question...what is the optimal amount of resizing? 0.002" short? Same as chamber size? A little long?
Thoughts?
My thought is because I use Winchester primers, that I don't have as much leeway on tolerating out-of-battery slamfires, and I should stick with sizing to about 0.002" short, but I don't think that I'll worry if I get a few in a batch that run long.
-J.
I have a series of sized brass that is about 0.001" or 0.002" shorter than the next that I used to measure my chambers to set up my sizing die for my Garands, which conveniently are within about 0.001" of each other...close enough for government work.
Anyway, I size brass to about 0.002" shorter than the longest case that will allow the bolt to close (stripped bolt without ejector). Up until this point all is right with the world.
I show him how fired brass won't fit back in the chamber, how commercial brass will fit without any trouble, how properly sized reloads fit just fine...and then I put in some HXP:
Untitled by jr_roosa, on Flickr
And the bolt barely starts to close!!!
I post this on the CMP Garand forum, and it seems to be old news that HXP runs a little long, but the Garand just smooshes it into the chamber without slamfires, out-of-battery discharges, or any small animals being harmed.
Then, they point to Hatcher's Notebook where it shows that GI .30-06 is supposed to be up to 0.006" LONGER in the shoulder than a Garand chamber, and that some machine guns back in the day had a chamber 0.011" short to MAKE SURE THEY SET THE SHOULDERS BACK ON CHAMBERING to prevent case head separation!
So...this begs the question...what is the optimal amount of resizing? 0.002" short? Same as chamber size? A little long?
Thoughts?
My thought is because I use Winchester primers, that I don't have as much leeway on tolerating out-of-battery slamfires, and I should stick with sizing to about 0.002" short, but I don't think that I'll worry if I get a few in a batch that run long.
-J.