between stock and barrel near the forend. In both these cases, bedding the action is required to provide support for the floating or pressure bedded barrel. Since the action ends up supporting the mass of the barrel, a poor stock to action fit will result in unacceptable shifting. Action The primary purposes of the firearm action are holding the cartridge in place in the chamber, and providing a way to ignite the propellant. In a single-shot action, little additional functionality is provided, while in a semi-automatic firearm the action also taps energy from the firing process for cycling to fire the next round. From an accuracy perspective, the primary goal of the action is to achieve a consistent placement of the cartridge in the chamber every shot. The term blueprinting, borrowed from high performance engine builders, is also often applied to the process of manufacturing or altering parts to have a desired (usually tighter) clearance than stock parts, and tightening the tolerances on critical dimensions to reduce clearance variations. Blueprinting a firearm action involves similar operations designed to tighten the clearances of a firearm action to ensure consistent and correct seating of the cartridge in the chamber. A typical set of blueprinting operations for a bolt-action firearm would include the following: Bolt blueprinting operations: Squaring the bolt face to the bolt diameter Ensuring the bolt is concentric in the action Squaring and lapping the locking lugs Sleeving the bolt (adding material to increase the diameter), then machining down for a precise fit to the action Receiver blueprinting operations: Making the action threads for the barrel concentric with the action centerline Making sure the breech face is square to the action centerline Making sure the recoil lug is square to the action Squaring and lapping the locking lug recesses These operations ensure that not only is the cartridge consistently and correctly positioned when chambered, but also that it remains correctly positioned during firing. Revolver specific issues The defining characteristic of a revolver is the revolving cylinder, separate from the barrel, that contains the chambers. Revolvers typically have 5 to 9 chambers, and the first issue is ensuring consistency among the chambers; if they are not consistent then the point of impact will vary from chamber to chamber. The chambers must also align consistently with the barrel, so the bullet enters the barrel the same way from each chamber. The throat in