I've got two McGowen .510 stainless barrels here.
THIS ONE IS SOLD. The short one 16.25" is a 1/10 twist, threaded for standard small shank Savage action, muzzle is threaded 1-14".
The long one 26" is a 1/15 twist, threaded for standard small shank Savage action, plain muzzle (no threading).
Both are chambered in .510 Beowulf, throated for BMG projectiles (.511 throat on reamer). Neck up 50 Beowulf, or 458 SOCOM, or turn the neck off of 50 Alaskan brass and cut an extractor groove (PTG will grind you a brass gouge if you want). Trim to length, fireform and go to town. Hornady 50 Alaskan dies work.
Both were ordered as straight cylinders 1.055", no contour - no taper.
For the money, rechamber or use for other projects.
Both could use a visit to the bead blasting cabinet to restore their finish.
Posting here first, will leave them up for a week or so then move them elsewhere if no interest.
$120 shipped for the short one(THIS ONE IS SOLD), $135 shipped for the long one (SOLD). PP F&F.