Bartlein is a barrel maker owned and operated by shooters who have been involved in barrel making for many years. They built state-of-the-art cut rifling machines which Bartlein says can hold uniform twist rates to the 4th decimal point. Several nationally known benchrest shooters shoot Bartlein barrels. Bartlein Barrels only uses single point cut style rifling, no buttong rifling and no broach cutting. All barrels are prelapped/honed before rifling and finish lapped after rifling.
Sinclair, Issue:5B, Page:238
SPECS: 22 call land/groove diameter: .218/.224. May require live pilot with appropriate sized pilot. SOLID PILOT MAY NOT FIT. 243/6mm land/groove diameter: .237/.243. 6.5mm land groove diameter: .256/.264.