This is good advice for reloaders and factory ammo shooters also.
I've seen one 44 Magnum round from one of the major reloaders who market reloaded ammo in this area fail to put the bullet through the barrel. It was lodged in the forcing cone of the Ruger Vaquero...
My friend who was shooting cocked the hammer immediately after the squib, and I was able to yell and get him stopped.
Then...
A Hornady Critical Defense .380 pistol load... no powder, but the bullet went all the way through the barrel and bounced off the target 7 yards away. No kidding, factory Hornady.
Dan