TLDW:  A reversible bull bbl w/ the gas port in the exact center of the length, & chambers & action threads on both ends.

I have a barrel (1.20" straight, no contour) that I shot 4500 rounds through one direction, then lopped off the chamber end, threaded it 5/8-24, then threade/chambered the old muzzle end.  Chamber is cut into fresh rifling and it shoots great.  Dunno if it'll last as long this go 'round.  Anyway, at one point I joked about using a receiver as a muzzle brake for a moment there when it was chambered on both ends.