Thread: believe it or not?

Originally Posted by veitnamcam

Both good points.

If you think of a pistol length barrel at one extreme and a 30 inch in something a bit over bore like 243AI with 105s requiring a slower powder like N165 or whatever.

With the slow powder in lets say a 4" barrel with the same load as the optimum 30'', that optimum powder for the long barell may not even reach peak pressure until the projectile is 6" down the bore.(a figure plucked out of my arse)

So in this made up situation, faster powder would almost certainly yield more velocity for the same peak pressure in the 4'' barrel but still be a long way short of 30'' velocity.

The best speed will always be from whatever powder has the highest average pressure for the projectiles full travel of the bore while staying under max pressure.

What is max? Well that is entirely up to the individual re loader but with the same components other than powder a reasonable comparison should be able to be made( 1 pound vs 6pound hammer to open bolt)

So If you are already getting the best velocity possible from "X" length and whack 6 inches of the barrel faster powder will not get back your velocity,but it may minimize your losses.

Thats pretty close. If its graphed then its area under curve that will increase velocity. Area under cure is usually best with the slowest powder that can give max pressure for the longest time ( flattest curve peak) but when the bullet is 4(ave) inches down the barrel the pressure is already dropping and acceleration is slowing. Using your pistol/ rifle example if you check reloading data given same chamber and bullet its powders from a similar burn rate recommended for both.