Bill, I must not have been here long enough to remember the Contender blow up. Would you mind telling the story again?
Happened back in the early 80s as I recall. Back in those days I picked up every case I found on the ground and took it home. Cleaned them up, inspected and loaded. I had more lots of mixed case heads than all the same in those days. I treated them all the same. If it said .44 Magnum I loaded it with the same load. As I recall at this time I was using 24.0 grains of W296 under a cast lead bullet weighting on average 242 grains dropped from Lyman 429244 mould.
There were two cases in the batch I was loading that were marked S&W on the head stamp.
When I load I put 50 cases in a block and drop the powder from a measure. I then examine them under a strong light to check that all have same appearance to check for over/under charged cases.
In the case of the two S&W hulls both looked way too full but all others looked same. I assumed I had some how over charged them even tho I didn't understand how. So I dumped the charges and inspected the cases to make sure ther was nothing inside them. They were clean and had no foreign objects in them. I dropped the charges again and again did the visual exam. Again they looked too full. So I measured the charges to be sure they had the correct charge and loaded them.
When I dropped the hammer on the first one the TC fell open the Pachmayr fore end landed about 20' in front of me. The charge had exploded the barrel out the top at the screw holes for the rear sight. It protruded upward a good deal and I think it damaged the lug as I recall.
I returned the frame and barrel to TC explaining what had happened. They replaced the barrel and declared the frame undamaged. No charge. It's not fun to have a gun explode in your hands, trust me on this. I wasn't injured and neither was anyone else near me but it could have been a LOT different.
Since then I do not pick up range brass and I do not mix case heads in batches. If I have for some reason an odd ball case brand with small quantities of them I trash them in a manner that no one else can ever get them.