I know there are a lot of variables between real life velocity readings and published load data but how much to allow for change in barrel length? I seem to remember reading somewhere it was almost 100 FPS (depending on caliber, powder, primer yada yada)
For example: I tested 2 strings of 10, 38 special. 158gr MBC 158 gr LSWC with 3.7 grs HP 38 out of a SW M 67 4" barrel. The gun is dead nuts accurate.
1st string AVG FPS 510, ES 25, SD 6.78
2nd string AVG FPS 514, ES 18, SD 6.16
So I can not complain about those numbers.
Hodgdons data says 834 FPS out of a 7.7 test barrel with 3.7 grs HP 38. I do not expect it to be exactly the same but how close should it be??
So over 300 FPS due to a 3.7 difference in Barrel length??
Lyman data shows 767 FPS With 3.6 grains out of a 4" test receiver
and 837 FPS with 4.0 grs
Is my Chrony Alpha that far off????
For example: I tested 2 strings of 10, 38 special. 158gr MBC 158 gr LSWC with 3.7 grs HP 38 out of a SW M 67 4" barrel. The gun is dead nuts accurate.
1st string AVG FPS 510, ES 25, SD 6.78
2nd string AVG FPS 514, ES 18, SD 6.16
So I can not complain about those numbers.
Hodgdons data says 834 FPS out of a 7.7 test barrel with 3.7 grs HP 38. I do not expect it to be exactly the same but how close should it be??
So over 300 FPS due to a 3.7 difference in Barrel length??
Lyman data shows 767 FPS With 3.6 grains out of a 4" test receiver
and 837 FPS with 4.0 grs
Is my Chrony Alpha that far off????