I once shot a antelope in Wyoming with a H&R handi rifle I built in 45 ACP and was checked by a game warden who was watching the whole thing from about a 1/2 mile away. I was hunting on Walk In land and was legal but when he checked my rifle I had a box of factory 45 Super ammo that I was using and on the ammo box it stated the ballistics but from a pistol length barrel.
Wyoming has a 500 ft. Lbs. minimum energy level for a legal hunting round and the ammo box showed 470 ft. Lbs + or - and he said it was not legal ammo I was using. I argued that out of a 18" barrel the round would have much higher muzzle energy but he didn't buy it. Lucky for me the landowner drove up while we were talking and he was able to calm game warden down and since the antelope dropped DRT he did not try to write me a ticket.
He asked me , do you have another rifle with you ? I said I did, I actually had 4 and he said do you have more tags and I said yea! 3 more and he said use another rifle please and drove away.
On another trip I shot a antelope with a handi rifle I built in 357 Mag. and was using Barnes XPB bullets and at approximately 100 yards it was the fastest I have ever seen a big animal hit the ground dead, not even a twitch. The 2 guys that seen me do it were really impressed as one of them had a Win. 270 WSM and the other was hunting with a 300 Weatherby Mag. and never seen a antelope drop dead so quick.
I also was checked by a game warden in WY after shooting a antelope and I was using a handi rifle again I built in a wildcat round and it was a .311 bullet cartridge and there laws require the OAL of the cartridge for that caliber to be 2.00" minimum. My wildcat was about .030 short but he let it go and asked to have one of my rounds for his cartridge collection so I gave him one. Later near sundown the intersection of the county road we were on and the main highway the same warden and several others were stopping all hunters and we were checked again.
Jed