These barrels for Glock are “Semi Fit”, meaning they general require little to no fitting. Barrels may drop-in, but expect some fitting to be necessary. Barrels are stock length for the designated Glock. Bar-Sto Precision Machine has been making some of the finest auto-pistol barrels since 1971. Bar-Sto barrels have been used by the U.S. Marine Corps Marksman Unit since 1977. All Bar-Sto Pistol barrels are machined from solid 416 stainless steel bar stock which has been heat treated 39 to 43 RC and 180,000 PSI tensile strength. Barrels are machined, bored, and rifled completely in Bar-Sto’s own shop. All barrels have a rate of twist of Mfg: Bar-Sto Precision Machine SPECS: Fits – Glock handguns. Construction – Stainless steel, hardened to 39 to 43 Rc.