I’m never surprised to see a velocity swing of even a 100fps between lots of even the best powders known. It happens. Nowadays I expect it and adjust accordingly.
Back when I got my first Mashburn I developed a load with 160 ABs and H1000, the load clocked right at 3200. Next bottle was 3050...
Put some good solvent on a patch, get the bore wet. Brush it with nylon, 20 strokes, run a wet patch.
If you wanna attack a carbon ring, get some JB or Iosso and work the throat.
I’d give it a shot at max length using RL26. That’ll be your best bet to see if it’s worth pursuing. If it works, I’d guess you’ll be in the 2800+ range for speed. That load would take you way out past 600 yard while maintaining plenty of speed to expand.
I have a 7x57 Mauser coming any day...
It’s funny how elk season sneaks up and happens every dang year. I know every year, I tell myself to start getting stuff ready, then all the sudden, it’s right there!
I used the plain old 150 AB in my Kimber 270, last year to take a good bull, at about the same speed as your load and had...
I have used the 175 ABLR to take a handful of elk with a few at 600 yards give or take a few yards either side. It’s a great bullet. When you mention wanting to use them in your Kimber I’d load up a test cartridge first and see if it functions. I love the Kimbers but the 84Ls are very limited...
Great shooting. I believe I’ve adopted your method. If I can’t get easy accuracy out of a rifle after proper assembly, it gets a new barrel. These days, dealing with a picky rifle just isn’t much fun and your shooting is incredible. That speed on that 150 AB makes it a do everything sorta load.