I never intended to build a high pressure gun, I just want to do a lot better with heavy .224 diameter bullets than the current offerings.
I believe 27XX FPS is the top end for a .223 Remington with 75 grain bullets. But in looking at the .228 Ackley, and the bigger Van Horn Express information I found, I should be able to gain almost 1000 fps over the .223 Remington.
Looking at my desire to fire the high BC 90 grain bullets, the 22-06 would thrill me if it sent 90 grain bullets down range with a muzzle velocity of 3400 fps. As long as it matched the velocity the 300's give to their high BC 200 grain bullets, it should equal them for long range, non-hunting uses, with less recoil.
Big cases allow lower pressures, as we see in the comparison of th 416 Rigby verses the 416 Remington. IF the right powder is available,and the performance goals are reasonable, there is no intrinsic reason a 22-06 has to be a high pressure barrel burner.
The 5.56X57 RWS must be loaded to very reasonable pressure levels because it has a significantly larger case than the 220 Swift, yet very little velocity gain. Like the project I want to do, its purpose was to launch heavier bullets. As we saw with the .244/6mm Remington, twist rates matter in cartridge design.
According to the part numbers my 7X57 and the 30-06 use the same follower in the M77, so the original cartridge isn't an issue in this project.
Thanks for the links to Mr. Howells info. He is always a great source of logical thinking on these subjects, though I was disappointed to not find the 22-06 in his book "Custom Cartridges". Hell if I couldn't have found another designer's work on this cartridge when writing that book, I would have made one up and put my own name on it.
All of you gave me ideas to follow up on in my reference books. Thanks for the good discussion.
