Regarding what jetinteriorguy and NoSecondBest said above, I did the following experiment today.
Procedure: 6 nickel .357 Mag cases:
1) Previously fired and cleaned, then measured
2) Resized and measured
3) Loaded with CCI 350 Mag primers, 2400 powder, 17.0gr to COL of 1.590”
(differences in COL may be due to case wall thickness, slight deformation of lead tip of the JHP, slight primer seating depth-??))
4) Fired each round and measured
5) Resized again and measured
Case Seated
Brand Fired Resized COL Fired Resized
1) R-P 1.275”1.280 1.581” 1.274 1.280
2) Win 1.285 1.296 1.588 1.285 1.297
3) WW Super 1.287 1.289 1.588 1.284 1.289
4) Win 1.287 1.292 1.590 1.286 1.292
5) WW Super 1.280 1.285 1.591 1.279 1.285
6) Win 1.292 1.297 1.588 1.291 1.298
I also loaded 5 more rounds without measuring the cases at all, with a target COL of 1.590”.
There was no discernable difference in accuracy between the two groups, shooting from a revolver rest at 15 yards. This would confirm what our two colleagues posted!
Sorry the table didn't come out right. I edited it twice but I think one can follow the data as it is.
Procedure: 6 nickel .357 Mag cases:
1) Previously fired and cleaned, then measured
2) Resized and measured
3) Loaded with CCI 350 Mag primers, 2400 powder, 17.0gr to COL of 1.590”
(differences in COL may be due to case wall thickness, slight deformation of lead tip of the JHP, slight primer seating depth-??))
4) Fired each round and measured
5) Resized again and measured
Case Seated
Brand Fired Resized COL Fired Resized
1) R-P 1.275”1.280 1.581” 1.274 1.280
2) Win 1.285 1.296 1.588 1.285 1.297
3) WW Super 1.287 1.289 1.588 1.284 1.289
4) Win 1.287 1.292 1.590 1.286 1.292
5) WW Super 1.280 1.285 1.591 1.279 1.285
6) Win 1.292 1.297 1.588 1.291 1.298
I also loaded 5 more rounds without measuring the cases at all, with a target COL of 1.590”.
There was no discernable difference in accuracy between the two groups, shooting from a revolver rest at 15 yards. This would confirm what our two colleagues posted!
Sorry the table didn't come out right. I edited it twice but I think one can follow the data as it is.