By Tom Armbrust:
To show what happens with various crimp depths, another test was run in the Hodgdon Ballistic Laboratory using one control reload and different crimp depths. Unless otherwise listed, the data in this text was created using a standard depth of 0.055, which is a bit short of 1/16. However, some manufacturing variations exist in which case handloaders are urged to use a factory equivalent crimp depth for that particular shotshell. The test reload was checked for pressure and velocity at 0.020 increments.
The test reload was assembled like this:
Shell: Winchester 12 GA 2-3/4” AA CF
Primer: Winchester 209 Primer
Power: 20.0 Grains of Hodgdon Clays
Wad: Winchester WAA12L
Shot: 7/8 oz of Lead Shot
The resulting ballistic data was as follows:
Crimp Depth Velocity (fps) Pressure
0.030" 1,308 f/s 9,300 PSI
0.050" 1,329 f/s 10,500 PSI
0.070" 1,351 f/s 11,900 PSI
0.090" 1,363 f/s 13,100 PSI
The importance of crimp depth, then, should be obvious: crimp depths to either the high or low side of normal will directly impact pressure/velocity results.
|
Hybrid Mode