First, thanks to all the guys who posted the tutorials for hand loading ammo (doc, tresmon, etc). And folks on other forums who lurk here,too. I hand load for two rifles: Rem 700 SPS-V in an HS Precision stock and a Springfield Armory M1A Standard.
Now, here's the deal. I have brass fired from both rifles as well as 1000 once fired mil brass. The brass fired from my rifles are my hand loads in LC, IAI, RP, WCC, and PMJ. The mil stuff is all LC 08. My hand loads were all the same bullet, charge and primer.
I measured the length to the lands on both of my rifles. The Rem is 2.935 (no surprise it's way long). The M1A is 2.863. Both measurements were done several times and an average was obtained.
I checked several pieces of brass in a Dillon headspace gauge. The brass from my Rem fit in almost perfect: very little stretch. The brass from the M1A was longer and needs resizing. The brass that's mil surplus was even longer. Just for grins and giggles I slid a mil case into my Rem and the bolt wouldn't go in all the way, let alone close. Again, no big surprise.
So I measured 5 fired cases:
Rem 1.560, 1.560, 1.5590, 1.560, 1.560
M1A 1.563, 1.563, 1.563, 1.566, 1.565
Mil 1.572, 1.573, 1.571, 1.5715, 1.573
With all of that in mind, the card that came with my M1A said it was headspaced to 1.632 and to use only ammo that was GI spec or commercial ammo made to GI specs. So, I just so happened to have an unfired LC tracer round and put it in my Dillon headspace gauge. It fit fine, just like all the brass I resize.
<span style="color: #CC33CC">How is it that even the LC mil brass, fired from GI weapons, isn't even close to the headspace on my supposed GI spec M1A?</span> There's a 0.059" difference between the longest LC case and the headspace (according to the card)on my M1A. So much for bumping the shoulder back for the M1A! <span style="color: #CC33CC">How is the brass so short even after fire forming?</span> All of my handloads were processed the same and made to data from Sierra's 5th edition. And there's only about 0.003" difference between fire formed brass from my Rem and the M1A.
Should it take several firings from the M1A to get the brass to grow enough to size it and bump the shoulder back a bit? Granted I used fire formed brass from each rifle, but the brass came out very consistently from each chamber so I don't think the kind of brass is an issue. Ideally I wanted to load only 1 kind of 308 round that would work great in my Rem and good in my M1A (good being hitting the black at 800m). After the measuring I did today and what's on the M1A card, I'm concerned that what I load for my Rem will have excess headspace in my M1A.
I haven't run any checks to see how the bolt on my M1A closes on the fire formed brass from the Rem, the M1A or the mil surplus stuff. I'm sure it will close on the Rem brass but will have to check the other two. <span style="color: #993399">Maybe the card is wrong and sizing for my Rem will bump the shoulder back about 0.005" for the M1A?</span>
Now, here's the deal. I have brass fired from both rifles as well as 1000 once fired mil brass. The brass fired from my rifles are my hand loads in LC, IAI, RP, WCC, and PMJ. The mil stuff is all LC 08. My hand loads were all the same bullet, charge and primer.
I measured the length to the lands on both of my rifles. The Rem is 2.935 (no surprise it's way long). The M1A is 2.863. Both measurements were done several times and an average was obtained.
I checked several pieces of brass in a Dillon headspace gauge. The brass from my Rem fit in almost perfect: very little stretch. The brass from the M1A was longer and needs resizing. The brass that's mil surplus was even longer. Just for grins and giggles I slid a mil case into my Rem and the bolt wouldn't go in all the way, let alone close. Again, no big surprise.
So I measured 5 fired cases:
Rem 1.560, 1.560, 1.5590, 1.560, 1.560
M1A 1.563, 1.563, 1.563, 1.566, 1.565
Mil 1.572, 1.573, 1.571, 1.5715, 1.573
With all of that in mind, the card that came with my M1A said it was headspaced to 1.632 and to use only ammo that was GI spec or commercial ammo made to GI specs. So, I just so happened to have an unfired LC tracer round and put it in my Dillon headspace gauge. It fit fine, just like all the brass I resize.
<span style="color: #CC33CC">How is it that even the LC mil brass, fired from GI weapons, isn't even close to the headspace on my supposed GI spec M1A?</span> There's a 0.059" difference between the longest LC case and the headspace (according to the card)on my M1A. So much for bumping the shoulder back for the M1A! <span style="color: #CC33CC">How is the brass so short even after fire forming?</span> All of my handloads were processed the same and made to data from Sierra's 5th edition. And there's only about 0.003" difference between fire formed brass from my Rem and the M1A.
Should it take several firings from the M1A to get the brass to grow enough to size it and bump the shoulder back a bit? Granted I used fire formed brass from each rifle, but the brass came out very consistently from each chamber so I don't think the kind of brass is an issue. Ideally I wanted to load only 1 kind of 308 round that would work great in my Rem and good in my M1A (good being hitting the black at 800m). After the measuring I did today and what's on the M1A card, I'm concerned that what I load for my Rem will have excess headspace in my M1A.
I haven't run any checks to see how the bolt on my M1A closes on the fire formed brass from the Rem, the M1A or the mil surplus stuff. I'm sure it will close on the Rem brass but will have to check the other two. <span style="color: #993399">Maybe the card is wrong and sizing for my Rem will bump the shoulder back about 0.005" for the M1A?</span>
