singleshotbuff
09-13-2006, 03:20 PM
Gentlemen,
I have read the posts in other threads about determining the burning rate of pulldown milsurp powder. I think I have it right, but I'd like some more experienced guidence.
The "donor" ammo is 7.62X54R, yellow tip, heavy ball ammo. Steel case, 180 (+/-)gr fmj bt. I pulled down 20 rds of the ammo and weighed the powder charges on an electronic scale. The average was 47.4grs, and the charges were surprisingly uniform. There was less than 1/2gr variance. Anyway, this ammo chronographs 2405 f.p.s. from my M44 carbine. I figure this to be 50.7 f.p.s. per grain.
Looking at my load & chronograph data, also using a 180gr bullet, 48grs of IMR-4320 gives 2383 f.p.s. out of the same gun. I figure this at 49.6 f.p.s. per grain.
50grs of IMR-4320 gives 2520 f.p.s. for 50.4 f.p.s. per grain.
The pulldown powder is even a stick powder with a physical appearance identical to IMR-4320. Equal weights seem to occupy the same volume.
Are these figures (50.7, 49.6 & 50.4) close enough to conclude that this powder has a very similar burning rate to IMR-4320? I hope so as 4320 is one of my favorite powders in several applications.
Are there other tests that I can/should conduct to verify my inference of this powders burning rate?
All help is appreciated.
SSB
I have read the posts in other threads about determining the burning rate of pulldown milsurp powder. I think I have it right, but I'd like some more experienced guidence.
The "donor" ammo is 7.62X54R, yellow tip, heavy ball ammo. Steel case, 180 (+/-)gr fmj bt. I pulled down 20 rds of the ammo and weighed the powder charges on an electronic scale. The average was 47.4grs, and the charges were surprisingly uniform. There was less than 1/2gr variance. Anyway, this ammo chronographs 2405 f.p.s. from my M44 carbine. I figure this to be 50.7 f.p.s. per grain.
Looking at my load & chronograph data, also using a 180gr bullet, 48grs of IMR-4320 gives 2383 f.p.s. out of the same gun. I figure this at 49.6 f.p.s. per grain.
50grs of IMR-4320 gives 2520 f.p.s. for 50.4 f.p.s. per grain.
The pulldown powder is even a stick powder with a physical appearance identical to IMR-4320. Equal weights seem to occupy the same volume.
Are these figures (50.7, 49.6 & 50.4) close enough to conclude that this powder has a very similar burning rate to IMR-4320? I hope so as 4320 is one of my favorite powders in several applications.
Are there other tests that I can/should conduct to verify my inference of this powders burning rate?
All help is appreciated.
SSB