Had a great morning at the range, with my instrumented M39. I have some results worth sharing!

WARNINGS: All chamber pressure systems require something accurate to calibrate by. Commercial test labs have access to special test rounds. My system uses chamber dimensions and the basic properties of steel. It gets you close, but you're never exactly sure. It's like having bathroom scales that you can't exactly zero--you know if you've gained or lost 5 pounds, and you know the differences in weight between you, your spouse, and the kids, but you're not exactly sure how much anyone weighs. Also, I don't have access to multiple batches of the same powder, and can't tell you how much that will affect results. Some brands of powder vary considerably from batch to batch. Different primers may give you significantly different peak pressures. With all that in mind--

XMR4350, 180 grain Sierra SP, CCI 200 primer, 3.000" COL

50 grains 2445 fps 43,000 PSI
52 grains 2625 fps 49,000 PSI
53 grains 2650 fps 51,700 PSI

Accurate 2520, 180 grain Sierra SP, CCI 200 primer, 3.000" COL

45 grains 2599 fps 57,000 PSI (one shot only)

XMR4350, 150 grain Speer SP, CCI200 primer, 2.880" COL

53 grains 2700 fps 41,750 PSI

Varget, 160 grain Speer SP, CCI 200 primer, 2.880" COL

46 grains 2610 fps 39,800 PSI
48 grains 2750 fps 44,800 PSI
50 grains 2840 fps 49,900 PSI

For reference, commercial Sellier and Bellot 180 grain clocks at 2600, and generates 58,200 PSI in my M39.

That was a 150 grain Speer, not a 160.

Denton:

Thanks for posting your results. I have been playing with a Polish M44 and I was working up a load using AA2520 although I was using a 150 grain bullet. I had to use a magnum primer to get things to even out, but the small amount of testing I did showed promise. If I ever get a day off from work, I'll finish my testing and post some results.