How do I know if my Colt AR-15 will shoot a .458socom?

If your barrel is marked .458 SOCOM, it will. Otherwise, it won't.

You should be able to get a replacement upper, complete with barrel, that will allow you to convert to teh new caliber.

You would have to get an upper that was chambered in .458 Socom. Depending upon the age of the Colt, it may not accept standard uppers without using an adapter pin. If the front pivot pin hole is 0.315” you will have to get a special pin. Does IN require handgun rounds to hunt with a rifle? If so, it would be much cheaper to get an H&R single shot rifle chambered in one of the handgun rounds. If you can use rifle rounds to hunt deer, there are other much more practical rounds for an AR-15 upper for deer hunting if .223 is illegal. 6.5 Grendel, 6.8 SPC, .243 WSSM, .30 AR, .264 LCB-AR, and a couple of others.

it will NOT>......unless u have put on a .458socom upper......

if u spent the 600+ to do that then YES it will....if u haven't ....or can't remember spending that much money on it then NO it won't......

firearms are LABELED AND STAMPED with the caliber/rounds they can/will use.....since urs is NOT stamped .458 then it will NOT shoot them....