Bore Guides are designed to align the cleaning rod with the center of the rifles bore. This insures that no damage can be done by a jag or brush. Bore Guides are machined with a snouth that extends into the chamber and seals with a silicone "O" ring at the end of the guide. This insures that solvent cannot run back into the action or trigger. The #1 Guide fits any Browning A-Bolt, Ruger 77, Dakota Mod. 76, Hart, Mauser, McMillan Signature, Remington (all) Sako L581, Savage Model 10, 110, 112, Stolle, Weatherby Varmitmaster, Winchester (all). CHAMBERED IN: 17 Fireball, 17 Remington