singleshotbuff
03-13-2007, 08:12 PM
Gentlemen,
As I have posted in previous threads, I have been working with IMR-7383 in various cartridges. So far only with Jword bullets. I had read in various other posts about temperature sensitivity with this powder, and since a lot of my load work up has been in cold weather, I decided to conduct a test of my own to determine how temperature affects this powder. I loaded the following representative load for testing at various temps from 20-90 degrees. It seems to be a mild load which SHOULD keep me out of trouble as the temp rises. The load is;
7.62X54R
Primer: Winchester large rifle
Case: Graf, neck sized
Powder: IMR-7383
Charge: 48.0grs
Bullet: 180gr FMJ BT
No crimp
Fired at 18 degrees, average velocity: 2271 f.p.s.
Fired at 70 degrees, average velocity: 2344 f.p.s.
A difference of 73 f.p.s., or approximately 1.4 f.p.s per degree of temperature difference.
Obviously, this only applies to this set of components and these temperatures. I plan to do further testing at different temps, to verify the numbers, and may try other cartridges and component sets. I just thought anyone working with this powder may find this info useful. Bottom line, as I see it, a max load worked up in winter may be a mite warm in the summer. I am finding 7383 to be a useful powder (especially for the price) but it does need to be treated with care.
SSB
As I have posted in previous threads, I have been working with IMR-7383 in various cartridges. So far only with Jword bullets. I had read in various other posts about temperature sensitivity with this powder, and since a lot of my load work up has been in cold weather, I decided to conduct a test of my own to determine how temperature affects this powder. I loaded the following representative load for testing at various temps from 20-90 degrees. It seems to be a mild load which SHOULD keep me out of trouble as the temp rises. The load is;
7.62X54R
Primer: Winchester large rifle
Case: Graf, neck sized
Powder: IMR-7383
Charge: 48.0grs
Bullet: 180gr FMJ BT
No crimp
Fired at 18 degrees, average velocity: 2271 f.p.s.
Fired at 70 degrees, average velocity: 2344 f.p.s.
A difference of 73 f.p.s., or approximately 1.4 f.p.s per degree of temperature difference.
Obviously, this only applies to this set of components and these temperatures. I plan to do further testing at different temps, to verify the numbers, and may try other cartridges and component sets. I just thought anyone working with this powder may find this info useful. Bottom line, as I see it, a max load worked up in winter may be a mite warm in the summer. I am finding 7383 to be a useful powder (especially for the price) but it does need to be treated with care.
SSB