I'm thinking about a new deer gun. I'm still getting the slug gun from my other thread(s) but I'm thinking about getting a rifle as well. I have been looking to get a new upper for my AR-15. I live in Indiana and the only "AR" calibers we can deer hunt with are : .458 SOCOM, .450 BUSHMASTER, and the .50 Beuwulf. I have a sundevils AR-15 in .223/5.56. If I get a complete upper in any of the listed legal calibers, do I need a different lower? How bad is the recoil between the three calibers? I shoot 12 gauge slugs and I'm pretty good with it. I can handle recoil up to 40 lbs just fine. Any suggestions?