Many years ago.
Early in my reloading experience, I blew the cylinder on a Ruger .357 mag blackhawk. Not something I am at all proud of, but I tell about it only to point out what reloading safety rules I broke to bring about this accident.
This was around 1973. I had been reloading rifle for 5 years, as well as shotgun. I bought a used .357 blackhawk with the conversion cylinder for 9mm. Of course I wanted to load for it, so off I went to the gunshop for dies, primers and bullets. I selected some Hornady swaged 158 SWC lead bullets. The only suitable powder I had on hand was HS-6. The loads in the pacific manual I had were from IIRC 4.0 to 6.6 grains. I set the scale to 4.0 to load a few trial loads. The first one blew a 3 chamber chunck out of the side of the cylinder. The chamber that the shell was in split straight accross, went under the next chamber, then out through the third chamber. The top strap was kinked, the rear sight was GONE!
No, I wasn't hurt at all! Surprised, yes, but I was wearing heavy gloves, I'm forced by poor vision to wear glasses, so I escaped injury. My dad was at the range with me, he had been standing to my right side. He moved just before the shot, or he might have been hit by the chunck of the cylinder. Some other shooters at the range were down about 10 positions, said they heard the chunck go over their heads!!!
Okay, so what did I do wrong? I took a couple of days to figure that out. I thought about it almost constantly, how did I screw up? Or was it a defective revolver? I looked over my reloading set-up that was still the way I left it after loading those shells. Finally I saw the mistake. I was using a hornady powder scale along with a RCBS uniflow measure. The hornady scale was the type that has the little wires that you position on the saw-tooth balance beam. The grain wire was on 4, the ten wire SHOULD HAVE BEEN on 0, it was on 10!! SO the load was actually 14.0 grains. HS-6 is a dense high energy shotgun powder, while it is a good powder for .357 mag, it will easily fill a .357 case to 3 times a normal load with room for a bullet.
Rules that were broken:
1. Double check your load data, then double check your settings.
2. Don't be in a hurry. I loaded them in a hurry the day before going to the range.
3. I was totally new to the reloading of handgun cartridges. I chose a bad combination at least as to the powder, I did not know that you could double or triple load a .357 case. So the powder level did not alarm me. Of course this was long before the internet with it's vast information.
As for the blackhawk, I took it back to the gunshop where I bought it. The gunsmith took one look at it, his ? was do you know what you did wrong? He sent it in to Ruger, they replaced it with another at factory cost, which IIRC was $95.00! I still have it, minus the 9mm cylinder.
