Stress relief/barrels - 04/06/13
I recently spoke with a barrelmaker at a gunshow and something came out of this conversation which I thought warranted discussion. When I asked the maker if he stress relieved his own barrels or sent them out, he replied that stress relief wasn't necessary since his barrels were cut-rifled.
The truth is that this is all well and good if the only stresses in a piece of barrel steel were those which may or may not be induced by the rifling process. If the barrel steel was perfectly normalized prior to any machining, cutting the grooves will not induce stresses as button rifling will. If the barrel steel is not perfectly stress relieved, the stresses will still exist after rifling and the barrel will probably warp when machined.
I mention this because many makers of cut-rifled barrels would have their potential customers believe that the rifling process is the only cause of stress in a rifle barrel. Ain't so folks. Steel may or may not be fully normalized prior to delivery. If it is not, the barrel should be heat treated to relieve stress prior to any machining of the outside contour. This regardless of the method of manufacture.
To state that a cut-rifled barrel is stress-free by virtue of it's method of manufacture is mis-information which really shouldn't be put out there. It is free of stress induced by the rifling method and that is all.
Over the years, I have had my hands on a half dozen barrels which warped when contoured. Half were buttoned and half were cut. None were stress relieved before or after rifling. By the way, I deal with this by simply not buying from that source again. Seems to work. GD
The truth is that this is all well and good if the only stresses in a piece of barrel steel were those which may or may not be induced by the rifling process. If the barrel steel was perfectly normalized prior to any machining, cutting the grooves will not induce stresses as button rifling will. If the barrel steel is not perfectly stress relieved, the stresses will still exist after rifling and the barrel will probably warp when machined.
I mention this because many makers of cut-rifled barrels would have their potential customers believe that the rifling process is the only cause of stress in a rifle barrel. Ain't so folks. Steel may or may not be fully normalized prior to delivery. If it is not, the barrel should be heat treated to relieve stress prior to any machining of the outside contour. This regardless of the method of manufacture.
To state that a cut-rifled barrel is stress-free by virtue of it's method of manufacture is mis-information which really shouldn't be put out there. It is free of stress induced by the rifling method and that is all.
Over the years, I have had my hands on a half dozen barrels which warped when contoured. Half were buttoned and half were cut. None were stress relieved before or after rifling. By the way, I deal with this by simply not buying from that source again. Seems to work. GD