case capacity variations--HELP!

[technicianjay]

Hello all,

I'm new to reloading. I've been reloading .308 with hornady 150gr. bullets with IMR 4895 and mostly Federal brass that was from factory loads that I fired myself. I necksized and used a 2.8cc Lee dipper (weighed in at about 41ish grains) and had great success.

I recently purchased some used brass off the EE--about 500 cases of mixed manufacturers and just reloaded 39, after careful inspection and full length sizing. Now the issue I'm having:

Quite a few of the cases seem to have less capacity than others. I loaded 43.1 grains of the above powder (the Lee manual says 45.5gr. is "never exceed", so I should be in the safe zone) and some of the cases fill to below the neck and some fill to roughly level with the neck base. When I seat the bullet (I seat to the cannelure, then crimp with factory crimp die), I can hear the powder rattling in the case when I shake them on the higher capacity cases, and can't hear it on the lower capacity cases. I don't think the load is compressed as I don't hear any powder crunching, but not 100% sure.

All these cases are marked ".308", so I ASSUME they aren't milsurp (?) as I've read milsurp cases typically have smaller capacity, although the primers on some have green or red laquer on them (but not crimped). Is this normal to find such seemingly large variances in case capacity? Again, I've full-length sized these and they've all been trimmed. And yes, I've weighed the charges and compared between a larger capacity case and a smaller one--there definately is a capacity difference between cases.

I would say the smaller capacity cases are as close to being a compressed charge as you can get (at only 43.1gr)...or do you really have to "crunch" the bullet down for it to be considered "compressed"? But my point is, if I were to fill to 45.5 gr., the "never exceed" charge, I'm pretty sure it would be a compressed charge, and the Lee manual doesn't show a "c" after 45.5gr which would suggest that it should NOT be a compressed charge.

I think I may tear apart all the ones that don't "rattle" and maybe bring them down to 42gr, or should I toss them altogether? Or should I just shoot the darn things and look for signs of high pressure

Sorry for the long post, just want some insight from some of the reloading gurus out there--I realize that buying old brass probably isn't the wisest thing to do, but I'm taking my time and carefully inspecting each case. I've also done a fair amount of homework, including searching for this issue on CGN (couldn't find it, so apologies if this has been already addressed) and reading "Modern Reloading" cover-to-cover, so I'm really trying not to blow my head off

 

[trevj]

<puts on best "Mystical Native Elder" voice>

"The signs! You must learn to watch for the signs!"



Sort them by make. Whatever you have the most of, load them, watching for the same sort of differences (should be minimal) and work up a load from there.

You want loads to whang away at tin cans, or to shoot reasonably accurately?

For just whanging, pick the cases with the lowest capacity, figure out a safe load with them, try it in the cases with the most capacity. If you get good case expansion with the same loads as work well in the smaller cases, yer good to go. Don't expect miracles for groups, but they should be reasonable stuff for plinking.

But definitely sort your cases and figure out what you have.

Just keep hoarding brass until you get enough of one type to be worth sticking too, or scrounge up enough coin to buy some, all the same.

Cheers
Trev

 

[cosmic]

Well - Your making a classic mistake - just because you successfully shot min load in Federal cases doesnt justify going to 43.1 gr in mystery cases - particularly in the stated calibre.
As above - segregate by brand, as varying case volume will affect performance. There is a good possibility that some of the 308 marked cases are milspec, or reject Milspec, signifying a reduced case volume, and the need to download even more. A few years ago, I was shooting the same min book load in commercial 308 brass and Hertenberger mil brass - it was very obvious that the Hert loads were running much hotter, likely close to max for my level of comfort. I should have backed off another 5% for the mil brass.

 

[technicianjay]

Thanks for the responses so far.

It's all part of learning. I didn't realize that there can be "rejected" milspec brass. That would explain what I'm seeing.

Looks like I'm going to rip a few apart and start sorting.