A 13/16" straight octagon barrel blank with a .40 caliber bore rifled with a slow twist, approximately 1 in 70". Blank is 42-1/2" long with 5/8-18 threads at the breech. The outside finish has some scattered brown from long storage. These barrels are unmarked as to a mfg. For use with black powder only. We have two examples at this price at the time of listing.