Hello, We all know not to use smokeless powder in an old BP-only gun... I won't do it, I swear. I wonder however why that it... BP burns faster and has a fast pressure rise time. It would seem logical that smokeless would be less harmful to old guns, assuming equal pressures. Do old guns blow up because people use too much smokeless? I assume there has to be another reason... I did read that old shotguns blew up because the barrel would thin out too soon from the chamber, but what about a revolver? A revolver barrel is much thicker than a cylinder chamber and there is the cylinder to barrel gap... So why would a cylinder fail with a slower burning powder and a load producing a pressure within the original BP specs? Is it because the pressure is applied for a longer period and the steel has more time to expand beyond its elastic limit? Gil.