Dirty Range Fun

not THAT kinda dirty, just keep readin'...
So last weekend I loaded up a few more rounds of 10mm, as I had a few more primers here and there I needed to put to good use as well as some more Berry's 180-grain plated flat-nose bullets.
I had a few left over from the last range trip with the 10mm...it's been a few weeks since I've taken the 10mm out, because I nailed my Shooting Chrony as I was testing a load I'd worked up before I even got the first reading on how hot it was. But I ordered a new one late last week and it came in Monday, so today I took it to the range to see how it worked out. I picked up another Shooting Chrony, but I took a step up to the Alpha model, the red one that will hold one 2- to 32-shot string and calculates average velocity, standard deviation and extreme spread. I took about 60 rounds today, with the following specs:

Case: Federal and a few Winchesters, three times fired
Bullet: Berry's 180-grain plated flat-nose
Charge: 12.1 grains of Accurate Arms No. 9
Primer: Remington 2 1/2 (large pistol)
OAL: 1.260"

Firearm: Kimber Stainless Target II

The only difference between this load and what I've loaded before was the primers, as I'd been using CCI large pistol primers before. And there was a bit of difference that I could see, from both the velocity readings and inspection of the pistol after shooting.
The load with the CCI primer was running just over 1150 fps on average, with individual shots running anywhere from 1120 to 1190, while the load with the Remingtons was running about 1120. I only took a seven-shot string, but the load was amazingly consistent through the string, anywhere from 1115 to 1128 feet per second; that's the lowest extreme spread I've had with ANY load I've worked up. I don't know how it would have changed if I had taken a longer string; maybe I'll try that next time out and see how it works.
But then again, I might not. The lower velocity I could deal with -- that much could be remedied with a higher charge, as examination of the cases showed it was running at about-normal pressures -- but it seems that not all the powder is burning, as the gun was a good bit dirtier when I was finished shooting than it usually is. I suppose one could also try magnum primers -- I've read of people using them a lot with the 10mm -- but I just don't know if I want to try that with a stock gun, as it'll ramp up both pressure and velocity if what I've been told is right. In any event, other than the dirty gun, it was a fun range day. But to twist the old saying, even a bad day at the range beats a good day at work. Better too that I managed to recover well over half my brass. I think I recovered about 50 out of 65, and it didn't take me that long either. Maybe I'm gettin' better at that too!