Very advanced. You might have to be a serious benchrest shooter to answer this.
Problem: I have acquired a rifle in the caliber of .300 Savage. Highly advanced for it's 1921 day of introduction, the 300 Savage had the approximate power of the .30-06 Springfield, but was built into a shorter case. Chuck Hawks says that much later, in the 1950's, the .308 Winchester, then the 7.62X51 NATO was developed from the 300 Savage, and of course we know of the provenance of the .308 Winchester.
Here's my personal problem: time has passed this caliber by. Once the most popular non-military deer AND elk caliber in the Northwest woods (Northwest hunters are cheap bastards, and used a lot of milsurp rifles to hunt with), it is still available, but there is little in the way of new cases to be reloaded, and the ammo itself commands a high price, almost $30/box. Hulls are over $25 for 50, and they are VERY hard to find.
I just completed some study, both in the SAAMI charts and by detailed measurement with a dial caliper, and it seems to me that the body of the 300 Savage cartridge case is virtually identical to the .308 WIN from the base to the start of the bottleneck. The only difference below the bottleneck is that the rim-cannelure (is that called the rebate or the extraction-channel?) is much wider in the .308 WIN than it is in the 300 Savage. I would guess that the 300 Savage, being designed for bolt or lever guns only, would not need as wide an extraction-channel as the .308 WIN, which was designed with semi-auto and full-auto battle rifles and MMGs in mind.
So, the big question is: Can the profile of a .308 WIN case be changed to the 300 Savage profile? Of course, the bottleneck in the 300 Savage is much steeper, it reminds me of Ackley-Improved calibers, and the actual case neck is much longer in .308 WIN, but that is just a matter of using a case trimmer on it. The main thing is changing the angle-profile of the bottleneck.
Can that be done?
If it can be done, there might be a few grains of difference in powder capacity between a re-made .308WIN/300SAV hull, but that can be measured and the powder loads recalculated so as to have the right pressures.
Secondary question: if the change can be made, will it best be made with dies or fire-forming?
Another secondary question: what will the longevity of these changed hulls be? My intent would be to use them with cast-boolit loads, which are much lighter in pressure than high-power jacketed hunting loads.
Some photos:
On the left is the .308 WIN round, a Hornady 168-gr AMAX match round. On the right is the 300 Savage round, a 150-gr Remington Corelokt. This gives you an idea of the cartridge profiles, side-by-side.
Another sXs view:
Well, there you have it, advanced gunnies. All advice welcome. Of course, I also know that I can just start hoarding the scarce 300 Savage ammo, but apparently, it is only made by Remington now, and I just don't like the Core-Loct bullets. Yeah, I have killed deer with them myself, and they did their job, but that little lead protrusion at the tip gets beat up easily, and I figure it causes some inaccuracy. I suppose I could pull the Core-Loct bullets from factory, and reload with my choice, that's always an option as well. I have a large selection of .308 bullets to try out in load development, everything from 110-gr up to 180-gr with several in between.
It's going to be a fun Winter, both at the bench and the range. Speaking of winter, it starts here in the PacNorWest in 2 days, so I need to get my bippy iun gear and put all the summer-living stuff away.
Cross-posted at Straight Case blog.