This bore guide was designed to clean barrels up to 30cal with a 1-1/16th in tenon. The cartridge specific pilot is press fit into the bore guide and contacts along the shoulder of the chamber so the brush/jag is fully supported all the way through the chamber into the bore. I find it much easier to clean barrels with them removed from the action. The bore guide has a solvent application port and is necked down to accept my 5/8 Cleaning Drip Tray linked below.

This was specifically designed for Curtis Actions barrels, but should work with minor modification for all 1-1/16th tenon barrels.

Recommended other items:

Rifle Barrel Cleaning Drip Tray - 5/8-24 by AngelicAnarchy - MakerWorld

M24 Barrel Vise by AngelicAnarchy - MakerWorld