Greydog... Equal pressure & valid comparisons? SAAMI for 30-06 & 280 is 60K. It's 65K for the 280 Ackley & the 270. The sharper shoulder in itself does not make brass withstand higher pressures. Brass is brass & is still the weak link in the chain. If you can find a copy of Ackley's book you can read his test results for yourself, but you might read something you dont want to hear. Paraphrasing from memory he says that the improved case, upon firing, grips the chamber walls better than a tapered case, thus reducing the bolt thrust. If I remember right there are a few tests to destruction of various actions in both standard & improved cartridges. I think there was a lever action chambered to 30-30 Improved tested with no locking mechanism, but am too lazy too dig out the books this morning. The day's a wastin' & the grass needs cuttin'.
MedRiver, I think you're short changing yourself with a 22" barrel, but your results will be interesting.
Enjoy your Ackley Bob. Dont be afraid to push the envelope a bit with care & within reason. Hoping you got a high # 03. IMR 4350 was the powder when I did most of the development. The 4831s filled the case well before before pressuring out. RL 19 & 22 were showing promise with 150s & 180s respectively. The new (plastic) jug of IMR4350 I got doesn't develop anywhere near the same speeds as the old (metal) can. Very disappointing. With the newer powders, RL17 has given good results with 150s. The biggest gains were realized with 150s & 165s so far, but with the plethora of newer slow burners, who knows? I will be trying some RL23 soon with 150s & 165s & may try RL26 with 180s.
