Here's a follow-up on the Shilen select match ratchet rifled #5 bbl I did for my CZ457 American. It's a glue-in - I didn't want to screw around with cutting the grub screw seats in the shank, so after I'd gotten the extractor grooves & the shelf for the feed tray cut in the breech of the Shilen, and finished it with 20ml graphite black/10ml tungsten CeraKote, I de-greased everything as good as I could with aerosol brake & parts cleaner, then spread some Loctite 609 over the shank & the interior of the action's bbl socket, then twisted them together. I put the action in the 4-jaw chuck of my lathe, jaws padded with leather belting, and ran the tailstock quill up against the face of the thread protector on the muzzle, put a little pressure on it, and left it sit overnight. After 14hrs, I pulled the bbl'd action out of the lathe, cleaned up any excess Loctite, then put it into the OEM stock, torqued the rear action screw to 25in/lbs, front to 20in/lbs, mounted the scope back on it, and went to shooting. Accuracy at 50yds was really close to as good as I'd hoped for with a good lot of SK Std+, and about the same with a good lot of SK LR Match. Everything else I shot in it was respectable, just not quite as good as those two lots of ammo. Overall, it's a big improvement over the factory bbl., and it now out-shoots my Varmint MTR by a fair margin, so the only thing I can do (besides selling the MTR) is to order another Shilen for it. Hope to have time to get the 2nd Shilen done before too long - went with another select match ratchet rifled blank, but this one's .850" dia straight, just .016" under the straight .866" OEM bbl on the MTR.