Welcome to loading for the 10mm auto. It is a fine cartridge that is well suited for handloading. Versatility is the name of the game here. My G20 has seen 180s as slow as 800 fps all the way to 1300+.
My take is a bit different than some on this forum. I'm not the guy that is going to start talking about how to go "full-tilt" with this cartridge. It is a high-performing cartridge already. Plenty of ways to get good performance without pushing things.
In my view, 800-X is not the best powder for 10mm auto -- especially if, 1) one is looking to load in volume, and 2) if starting out as a new loader to the cartridge.
It does give some high performance, but one must load a good ways beyond published maxes to get anywhere. This is not where you'd recommend someone new to a cartridge to go. Blue Dot and Accurate no. 9 will get better top performance while sticking with proven book loads. Book loads for Longshot will be similar to 800-X in terms of velocity. I first-hand experience with all of these powders that I mention.
For volume loads, 800-X meters like crap. Basically, it doesn't meter. So hand weighing each individual charge is on order with this powder. So, not conducive to high volume.
You mentioned "practice ammo." To me this implies ammo that you'll shoot a lot.
Longshot is a good metering powder that give respectible loads when following Hodgdon book data. 10.5 grains of Accurate no. 7 under a 180 gr FMJ will give great all day long blasting fodder in the mid 1100s fps. All of the Accurate powders (5/7/9) meter supurbly. 10.0 grains of Blue Dot under a 180 is great too. 1150 fps.
I recommend Accurate no. 9 as the go-to for when you want to try to go full out. This powder gives the highest performance for 155s, 180s, and 200s when sticking to book data out of all of the powders I've tried. It meters great, and you almost can't get an overcharge in a case since it has complete case fill. It is true that some are getting higher velocities with 800-X by seriously boosting book maxes. But, I am not so sure of the value of chasing that last 50 fps. A 200 grainer @ 1200 fps from a bone stock Glock 20 is plenty for me.
Lately I have been shooting light charges of Accurate no. 5 and WSF for "gamer" loads. Again, this cartridge is versatile, and so is the Glock Model 20.
EDIT: Skip the SPP 10mm brass. It is rare. I wouldn't waste time developing loads for those at all. Standard LP primers (I prefer CCI 300s) are best. If you can't find standard LP primers, mag primers will work ok too. Reduce charges and re-work the loads. I get better performance with standard primers.
"There is nothing like looking, if you want to find something." Thorin Oakenshield
Last edited by Taterhead; 07-09-2013 at 01:00..