How Does Deep Cryogenic Processing Relieve Stress?
Residual stresses exist in shotgun barrels from the original steel forming and forging operations, along with the many different machining operations needed to finish the barrel. These operations create a complex, invisible, random pattern in the steel. A steel barrel expands from the heat generated by firing, hut stress impedes expansion and steel barrels often warp randomly oft axis as they are heated by sequential firings. Residual stress can cause a barrel to progressively warp an arc as it heats more from each round fired. A title barrel placed in a vise and fired repeatedly will often show a resulting arc of round placement at the target. No two barrels are the same, but the effect has a memory and will continue with each group of shots fired. The “loose-cannon effect” is measured in microns at the barrel end, but the distance to the target amplifies the problem, causing widespread groups or patterns. The problem is not a crooked barrel but one which moves after repeated firing.
