I have decided that AA #9 is my powder for 10mm. I was testing with a Glock 20 Gen4, 24 lbs RSA, and KKM barrel (standard length), target was 15 yards from me with chrono at 10 feet, shooting off bags. Max charge of 13.5 grains of AA #9 seemed a little too stout for me, but gave good chronograph numbers, so I went back to my workup research and loaded some at 13.1 (on Dillon XL 650 - using powder drop). Side note is I wanted 13.0 grains, but had a hard time getting powder drop zeroed in on it, so I settled on 13.1 grains! All new Starline brass. And Accurate #9 was purchased this year when it started being available again. (I was actually hoping to get average velocity around 1250 fps, so might drop another couple of 1/10s on next run)
String: 6
Date: 7/18/15
Time: 10:33:20 AM
Grains: 180
Hi Vel: 1275
Low Vel: 1263
Ave Vel: 1269
Ext Spread: 12
Std Dev: 3
10mm AA #9 13.1 grains Hornady 180 HAP 1.250
Velocity Power Factor Ft/Lbs
1271 228.78 645.603
1271 228.78 645.603
1269 228.42 643.572
1274 229.32 648.654
1266 227.88 640.533
1267 228.06 641.545
1275 229.5 649.673
1267 228.06 641.545
1267 228.06 641.545
1263 227.34 637.501
(http://www.chriswall.net/photos/10mm_AA9.jpg)
One issues i did have is some failures to feed, I assume it is from the 24 lbs RSA and was too lazy to dig out the 22 lbs one or the stock one as no changes have been made to the XL650 and all other rounds out of it have been fine (OAL 1.250", crimp 0.422" - 0.423" finished product fit Dillon 10mm case gauge). Slide seemed to be catching the top part of the shell casing instead of the end of the case on a few shots.
Data from 13.5 grains:
String: 4
Date: 6/6/15
Time: 9:20:40 AM
Grains: 180
Hi Vel: 1307
Low Vel: 1288
Ave Vel: 1298
Ext Spread: 19
Std Dev: 6
AA #9 13.5 gr - Hornady 180 gr HAP - Federal 150M - OAL 1.250
Velocity Power Factor Ft/Lbs
1303 234.54 678.52
1303 234.54 678.52
1303 234.54 678.52
1299 233.82 674.361
1288 231.84 662.988
1288 231.84 662.988
1307 235.26 682.693
1295 233.1 670.214
1294 232.92 669.18
1300 234 675.4
Some great numbers! Hornady does make some great bullets...thanks for the range report!
Good shooting!!
A9 is my favorite 10mm powder too. Hornady XTPs and A9 are tough to beat for accuracy. The ONLY downside to A9 is that it is not efficient. Those hefty charge weights will suck down a can of powder pretty quickly. But since powder is the least expensive part of the equation, it isn't a big deal.
I too had the identical issues with heavier spring weight and heavy 10mm loads. The stock RSA cleaned that up 100%.
I had the same result w/Longshot and AA9. I finally found I had over sprung. The key came whenI aded a polyurethane buffer to the RSA and the failures to feed increased dramatically., pulled the 22# spring and buffer and all is well in the world again.
wow that is a nice group and as far as your Dillon I wouldn't know about that ,that is a Dream set up for me all I have is. Lee breech loading single stage but I did run into some similar problems with FTF's when I first tried a 24#rsa with stout loads of longshot and berry's 180 fmjs when I switched to the 20# and oem rsa the FTF's stopped bit I got slightly better groups with the 20# rsa .