I've tended to want to neck up a lot of common cartridges for use in common rifle platforms. Most of my ideas involve wanting to have versatile cartridges that can fire pistol caliber bullets the same weight as the parent cartridge's standard load, or at least a normal one for it, at higher energy and probably the same velocity and short range trajectory. They would generally be loaded to function in a certain semi-auto carbine. It would serve for hunting and LE/personal defense alike, delivering high penetration in game and high energy delivery in CQB using pistol bullets at rifle speeds (probably less penetration, a LE safety issue)
Concepts include:
1. 35-223 0.354"-0.358" caliber cartridge, essentially straight walled with a rebated rim to the same diameter as a 223/5.56 NATO, and designed to work in the AR-15 system.
2. 35-7.62x39 Same caliber, but in a 7.62x39mm with shoulder diameter increased to 0.421" so that it has the same stacking geometry as 223 and could feed in M16 mags. Could work in Mini-30, AK, or AR-15 with 7.62x39mm bolt. I know the Russians have something similar with subsonig high weight AP bullets. but it's unimportable and i'd rather have something that usually uses lighter bullets.
3. 358 WSM. A 358 short magnum that is actually a magnum, not the ballistic equivalent of a Whelen (which I have nothing against).
4. 350 RUM I like 35 calibere and wish there were a round in this caliber decent enough for all the predators on the continent.
5. 408, 308 Winchester necked up to 40 cal, using 40 S&W pistol bullets among others. Could be used in pumps and autos chambered for 308 Win.
6. 45-284, uses pistol or rifle bullets 0.451-0.458 (or whatever range is feasible) with the common 0.473" base, making it suited for slightly stronger pumps and autos than the 308.
7. 458 WSM More energy than 450 Marlin, but not the terror of the 458 Win Mag. Would attract buyers to big bore that otherwise wouldn't dig it.
Is it fair to assume a 408 would push a 180gr 40 caliber bullet at least as fast as a 308 would push a 180gr 308? Seems to be the case as the 243 WSSM has a higher velocity with 55gr than the 223 WSSM with the same bullet weight, as the pressure acts on a larger area, resulting in greater acceleration force, though it's countered by the pressure reduction in a wider caliber barrel.
I've never wildcatted, only handloaded with a friend, so I'm just going over ideas. I'm sure a few of these have been done before, would like to know how to find out about them.
