Check out this little bugger I just put together:
Custom Built AR45 SBR based on the CMMG Guard.
-CMMG Guard 45 bolt carrier and 8" barrel in .45 ACP/.45 Super/.450 SMC
-Anderson MFG .458 Socom upper
-MVB USC Magazine Adapter
-H&K USC Magazines
-Seekins Precision NOXS 7" rail