I would be interested in what the real pressures would be with 83 and 84 grs. of IMR-4320 as I am sure the factory didn't use that powder.
Like most, I do not have pressure testing equipment, and can only go by the usual tell tale signs, but that has kept me in one piece for many years now..With those loads I got 2350 FPS (albiet I always used a 26 inch barrel) and the primers, were good, no extractor marks, no sticky bolt lift, reloaded a single case 10 times, with 3 trims, according to my files. That indicates to me that I was not working at 70,000 PSI, but like I said, I have no other means of testing with any of my rifles. Also in this conversation, one must allow that the 458 Win. boys are operating at high pressure also. sooooo?
I wish I would have sent those loads to Mike at Northfork. I got into a conversation with the 404 Jefferys wherein 95 grs. of IMR-4831 gave me 2653 FPS in my 27 inch original Jefferys, and the pressure thing was challanged...Mike did the testing, got 2590 FPS in his 24 inch test barrel and safe pressure. He allowed my loads were safe and with the additional 2 inches of barrel that I was in the ballpark...The recoil was intense, so I loaded them at 93 grs. for a bit over 2400 FPS for hunting, which I intended to do all the time.
Like most, we can only play with what we have to work with. I feel the 458 Lotts that I played with were safe, at least I hope they were and I shot that load quite a bit without any problems.. I used magnum acitons on my Lotts and though I don't recall offhand I strongly suspect I have long throats so as to seat the bullets out to match the magazines. that in itself would releave a good deal of pressure.
Anyway I submit the above for what its worth..I don't shoot either the 458 Win or the Lott as I went to the 40 calibers almost exclusively some years ago, as I have bursitas in my neck and shoulders from shooting those big kickers. The 416s are about my limit these days. Age and caliber are definatly related
Additionally by way of edit, I would like to add that adding 100 FPS in a big bore caliber is very sugnificant. Adding a 100 FPS to a 458 Win. makes it a considerably better killer and if pressure was OK then none of the conflab would have ever come about...
You cannot apply the same set of rules to a big bore that you can to a high velocity magnum..100 FPS in a .270 or 300 whizbang means nothing, but in a 40 caliber with bullets of 400 grs. and up it means a lot and it gets more so as the bore size increases..add 100 FPS to a 577 or a 600 and your bicuspids will fly and the difference in killing effect can be observed.
