Why is slower powder working better in my '
I've used IMR 4064, Varget, IMR 4350, H4350, H4831SC, and RL22 in my 30-06 JDJ.
I get excellent accuracy with the RL22 and C-T 168 BST's (one group was a near one holer). I also get extremely tight SD's and extreme spreads from H4831SC (single digits on the SD's). I also get good accuracy from all the powders mentioned above. My hunting load consists of IMR 4064, but I intend to use H4350 more in the future after I chronograph some loads that have shot extremely well. I didn't get these clocked due to problems with the speedometer at the time.
I am of the opinion that the slower powders still are burning virtually all of it in the barrel, even in a 15" pistol barrel. Some of the people in the industry, such as Rick Jamison, have demonstrated through the use of instruments such as the PBL 43 that most of the powder, if not all, is burned within a few inches of the chamber. This can be seen in the fact the his graphs show, that upon ignition of the powder, the pressure spike occurs while the bullet has traveled only a few inches. The graphs then display a gradual drop in the pressure.
Since the gaseous state of the powder will occupy roughly 100 times the space as the same mass of the powder in a solid state, it is clear that what comes out of the end of the barrel is the gaseous state of the powder. Since some cartridges are noted for displaying balls of flame at the end of the muzzle, then what is observed is the gaseous state of the ignited powder. Slower burning powders would be more apt to display this ball of fire. RL22 displays a quite large flame in front of the barrel (I can't see it in daylight, but observers have pointed it out to me...)
In simplistic terms, accuracy is merely getting the bullet to exit the barrel when the harmonics of the barrel are at their "best" (ie - barrel is momentarily stationary). That's why some loads shoot good, and some don't. OF COURSE, this assumes that a quality barrel, and quality ammo is involved. Poorly constructed barrels and ammo have the odds stacked against them from the beginning. Changing powder charge wt., OAL, and/or primer can and often does impact the accuracy of a given set of components.
So much for my 2 cents...
Regards,
Rog
