So I am loading .357mag for a S&W 686-6+.
Using Win231 and powder coated 158gr RN bullets sized at .358, win. SP primers. Cases are mostly Aguila nickle plated, some Federal, few Winchester.
Load is 6.0gr of powder with a cartridge length of 1.590 (Lee load data states min 6.2gr/ max 6.7, Min OAL 1.540). Crimped in crimp canelure with a FCD.
Seems like a mild load, except that after examining 21 cases fired, 7-10 show some degree of primer flattening (from slight to overt) and some have very slight firing pin indent cratering, barely. The rest seem to be just fine, nice round shoulders. No loose primers. I noticed a significantly louder report and more blast from a couple (loudness prompted me to pop cylinder open and look ). Some had stickyer extraction than others but nothing extreme.
Was running a chrono and got an average of 1030fps, with a low end of 994fps which happened to be one of the loud ones.
So I stopped shooting after the third cylinder and pulled the remaining 23 cartridges I had loaded with an inertial hammer trying not to lose any of the power and weighed each one. Did not find a single load over 6.0. If my powder measure was at fault and dispensing erratically I think it would show in the other half of unfired cartridges. There is alway the chance of having double charged but I think that would have been more catastrophic-like.
Case length of fired cartridges are all about 1.280-1.285. There is nothing unsual about the gun that I can see. Cylinder throats do not seem to be overly tight and the gun was clean, all cartridges chambered freely.
What can be going wrong here?
Using Win231 and powder coated 158gr RN bullets sized at .358, win. SP primers. Cases are mostly Aguila nickle plated, some Federal, few Winchester.
Load is 6.0gr of powder with a cartridge length of 1.590 (Lee load data states min 6.2gr/ max 6.7, Min OAL 1.540). Crimped in crimp canelure with a FCD.
Seems like a mild load, except that after examining 21 cases fired, 7-10 show some degree of primer flattening (from slight to overt) and some have very slight firing pin indent cratering, barely. The rest seem to be just fine, nice round shoulders. No loose primers. I noticed a significantly louder report and more blast from a couple (loudness prompted me to pop cylinder open and look ). Some had stickyer extraction than others but nothing extreme.
Was running a chrono and got an average of 1030fps, with a low end of 994fps which happened to be one of the loud ones.
So I stopped shooting after the third cylinder and pulled the remaining 23 cartridges I had loaded with an inertial hammer trying not to lose any of the power and weighed each one. Did not find a single load over 6.0. If my powder measure was at fault and dispensing erratically I think it would show in the other half of unfired cartridges. There is alway the chance of having double charged but I think that would have been more catastrophic-like.
Case length of fired cartridges are all about 1.280-1.285. There is nothing unsual about the gun that I can see. Cylinder throats do not seem to be overly tight and the gun was clean, all cartridges chambered freely.
What can be going wrong here?