I have read a lot of ways actions(and triggers) can be blueprinted but what the OP wants to know is exactly what it means. (in shooting, not racing)
Blueprinting, or truing, an item such as a trigger is an attempt to bring that part closer to the design specifications, hence the term blueprint. For instance if a part is cut with a dull tool and an extra .001 of material is left on the part, removing this material to match the original design would be considered blueprinting. In a trigger, precise angles and surface finishes are required. If a 90 degree angle actually measures 89 degrees, or the sear is rougher than required, the trigger may not function as designed. Correcting the angle or polishing the sear would also be considered blueprinting. A complete blueprint, or truing, would include correcting any existing inconsistencies in the item. Since you are not starting with a fresh piece of steel, you can only make the part as close as you can to spec with what you are given. Angles may be too far off to square up within the tolerance given, or too much material may have already been taken off during manufacturing. You may end up with a square and striaght part, "blueprinted" that is actually out of spec. Blueprinting the threads of an action, if they are far out, can require a custom fit barrel thread rather than a precut thread on something like a switchbarrel.
Blueprinting, or truing, an item such as a trigger is an attempt to bring that part closer to the design specifications, hence the term blueprint. For instance if a part is cut with a dull tool and an extra .001 of material is left on the part, removing this material to match the original design would be considered blueprinting. In a trigger, precise angles and surface finishes are required. If a 90 degree angle actually measures 89 degrees, or the sear is rougher than required, the trigger may not function as designed. Correcting the angle or polishing the sear would also be considered blueprinting. A complete blueprint, or truing, would include correcting any existing inconsistencies in the item. Since you are not starting with a fresh piece of steel, you can only make the part as close as you can to spec with what you are given. Angles may be too far off to square up within the tolerance given, or too much material may have already been taken off during manufacturing. You may end up with a square and striaght part, "blueprinted" that is actually out of spec. Blueprinting the threads of an action, if they are far out, can require a custom fit barrel thread rather than a precut thread on something like a switchbarrel.
