Luth-AR 20" Bull Barrel Complete Upper Receiver Assembly

Luth-AR builds this one as a finished upper: receiver, 20 inch bull barrel, and the barrel nut work all done, ready to pin to a stripped lower.

Bull barrels are heavy on purpose. The extra steel around the bore soaks up heat and resists the whip that walks groups open as a thin barrel warms, so a bull barrel upper turns a general purpose AR build into a bench or varmint rifle without touching the lower half at all. Twenty inches is the classic rifle length for that job, long enough to wring velocity out of a load and short enough to still handle off a bipod. Check the caliber stamp on the barrel and the gas system length against the rest of your build before you order.