Ok, after several discussions with friends about the new short mags and "effeicency" and all that usual stuff, i started wondering about how the barrel length effects optimum powder burn rates. One the common views is that the short mags can get away with shorter barrels because they use faster powders. Is this true?
One buddy of mine is convinced that the 300 wsm can get away with a shorter barrel than his 300 win mag and still be as effiecent. Some of the loads i have seen for the wsm use the same powder, like rl 22, so why would one need a longer barrel than the other? Maybe because the wsm burns less powder? Not that i am convinced that there is an "optimum" or necessary length after reading Charlie Sisk's thread on barrel length and velocity. It just seems the logic that the wsm doesnt need as long of a barrel as the regular mags doesnt add up. <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />
My thought was that case and bore dimensions are the factors that decide what burn rates are ideal. If the powder is mostly burned in the first few inches of the barrel anyway, does the same cartridge with a shorter barrel need a faster powder than the standard length barrel? I have a 30-06 with a 20 inch barrel, and with IMR4831 i was getting a significant flash out the end of the barrel at dusk, with 4064 the flash went away. I figured it was unburned powder that caused the flash, so i assumed with faster powder i was getting less flash, thus more velocity (this was a few years ago before i had access to a chronograph). After all my recent "internet schooling" now im not so sure. Dad and i also wrongly figured that the short barrel would allow us to load to higher than listed charges and the pressure would be lower due to a shorter barrel. Now i realize the pressure peak is past before the bullet leaves the gun, so barrel length should have no effect on chamber pressure. At least i think this is the case.
Dad recently aquired a model 7 in 7mm-08 with a 20 inch barrel, and he pretty sure he needs to load it up with some faster than normal powder to compensate for the short barrel (like we did with my 30-06). I dont know if i agree with him. Especially after reading Charlie Sisk's thread on barrel length and velocity.
What do you guys think-- Does barrel length effect optimum burn rates? Or is it case size or case dimensions that effect it?
