I'm new to loading the 10mm, but so far I'm quite impressed with the cartridge. Last week I loaded up some expirimental rounds with Ranier 155 grain bullets and HP-38 powder. Using data from the Hodgdon manual, I loaded five 10 round batches that incrementally progressed from the starting load to the max load. Then I was off to the range with my sand bag and Chrony. During my testing, I was pleased to see groups in the 2-3" range @ 25 yards; however, as my powder charges increased to a point beyond 6.5 gr (a midrange load), accuracy began to go to hell very quickly. At the maximum load of 7.3 gr, velocity was running around 1100 fps, but it was hard to even keep shots on the target. I suspect the relatively soft Ranier bullets were skidding the rifling as pressure/velocity increased. I thought I'd post my obervations here and see if those of you more experienced with the 10mm agree with my supposition, or if you think there might be some other problem. As it stands, I have some nice, accurate loads, albeit in the .40 S&W velocity range; but, I'd like to take advantage of the greater ballistic capabilities of the 10mm if I can do so while maintaining acceptable accuracy.
Thanks,
HRF

I too just recently started loading for the 10mm. I am trying AA#2,#7,#9 and bluedot. I am shooting a 610 4" and a 1076. I do all my load testing at 7 yards and clock all velocities. I have found several loads that you can cover with a quarter. Tested 200gr Rainers but they seem to show leading at high velocity (1129 fps). You can email me if you want to share data.

I don't like the plated bullets at the higher velocities for the reasons listed.

I do like the Hornady XTP line up for hunting.

The Remington Golden Sabers are good to go! As I understand the Gold Dots from Speer are said to be plated...I'm not sure. Speer has always been my choice for rifle and some pistol bullets.

I do Cast and load 175 grain Lyman TCBB up to 1100 fps for target practice with good accuracy in the 10mm and 40S&W loads with Blue Dot.

I never have had that type of problem with Ranier/Berry's plated bullets. Now I haven't loaded many in the 40/10mm cartridge either.

I have a suggestion though. Get some jacketed bullets of the same weight and load them to the same charge weights. Run them again and see if it's the bullets or something else.

Are you using lead data for the Ranier's? That is what they recommend. I for one would find it hard to believe they are slipping the rifling, but what do I know?

I know a friend of mine who is driving some Ranier 135's at 1800 fps from his Glock with the aftermarket KKM barrel with good results using IMR800X powder.

RAinier does not recomment their bullets at much over 1,000 fps. It isn't what they are designed for. Plated and jacketed are not the same thing.

Yah. I started loading Rainier plated because of the those who don't clean their Glocks problem. They should be treated more as a lead round than a jacketed round.

It is hard to get 10mm energy from a plated projectile. They are great for plinkers but if you want .40S&W+ performance, stick to the thicker jacketed.