Okay fellas, try not to rip me too much of a new one here if this sounds like a stupid idea. Keep in mind that, as of now, this is just a theoretical build for some time long in the future, when I actually has appropriate monies to attempt something like this. If I were to take a Benelli R1 semi-auto rifle and rebarrel it in .458, could I then, theoretically, load the rifle for .458 whisper-type rounds? A Benelli R1 is chambered in rounds up to .300 and .338 Winchester magnum, which share the same rim size as the .458 Whisper's parent case, the .458 winchester mag. The total length of those rounds generally tops out at around 83-85mm, or about 3.34 inches. If I were to load a .458 whisper-type cartridge with long bullets, would this put the overall length of the cartridge at around the same as that of the parent cases? Also, it is impossible to find any sort of ballistics on a .458 whisper cartridge, so I was wondering if anyone has had any personal experience with one, and can tell me what kind of punch it packs. What kind of game animal can be taken with a .458 whisper loaded with, let's say, 500 grain pills, at subsonic velocities? Any replies will be appreciated, but don't forget to be nice, I'm still a noob to this sort of thing.