The “Blueprinting” Process for Barrel Shoulder/Lug Fitting
Jim Borden, the very knowledgeable owner of Borden Accuracy, provided an interesting historical insight about barrel fitting and the term “blueprinting”. Jim has posted on his Borden Accuracy Facebook page an explanation of the term “blueprinting” as it originally was used with respect to barrel/shoulder/lug fitting.
Barrel/Shoulder Fit and Blue-Printing
Jim told us: “Something often overlooked on barrel installation is the shoulder fit. Many are so overly obsessed with doing a crank-on fit of threads that the shoulder contact is overlooked. Full, solid barrel shoulder to recoil lug or action face is critical to optimum accuracy and precision.
Many years ago part of the ‘blueprinting’ of an action was the use of Prussian blue to ‘blueprint’ lug fit, thread fit, and barrel shoulder fit. It was a colloquial expression that had nothing to do referring to a blueprint or drawing of the action.” Bet you didn’t know that!
About the photo below, Jim noted: “the fuzzy look on the threads is a liberal coating of Never-Seez thread lubricant.”
Look carefully to see the Prussian Blue applied to the barrel shoulder, plus Never Seez on threads.
