I have a weird one here... I bought a box of 180gr X-Treme FN bullets on recommendation that they were great for the range.
I have a G20sf with the 6" KKM barrel, and so far have only reloaded with Hornady's XTM bullets with no problems.
But ever since I've been loading the X-Treme bullets, I can't hit the broadside of a barn. Even stranger, I get better grouping with the factory barrel with the X-Treme bullets than with the KKM; grouping is still pretty bad with the factory, but, it's noticeably better. I say horrible as in from 30ft, with the KKM barrel, I can't put but maybe 1 shot on a 8.5x11" target downrange out of 20. The factory, I can get maybe 3-4 out of 20 on target. Shooting longer distances today on the rifle range, shooting at the 100yrd targets, I'd have some go completely over the target backer, and some would dive into the dirt halfway to the target.
I've tried with several different powders (Power Pistol, Longshot, WS231, Titegroup, 800-x) and they all perform equally as horrible, so I'm not thinking it's a powder issue at this point.
Is there anything with plated bullets and the KKM barrels?