TC1
I didnt test the two you mentioned, but the 300 RUM , I tested with H870 and H4895. Same results as a 308 or 223 or any others. In my opinion and testing, modern smokeless gunpowder burns like modern smokeless gunpowder. No amount of case shape, advertising, endorsements, etc, has any effect. Dont take that as the gospel, thats just what the chronograph and strain gages tell me.
Charlie
Fascinating! I would have bet folding money that the 300RUM with H870 or other slow burning powders would have shown larger velocity gains with the long barrels than would have a more pedestrian cartridge using powders of moderate dosage and burn rates.
So, how does one determine now an optimum barrel length for a given cartridge and bullet? Surely we are not suggesting 16 inch barreled 257STW's. Not being a smart aleck, genuinely curious and want to think this through or perhaps begin creating a formla. Someting like with X size bore and Y size case capacity velocities are optimal and will not sufffer significant velocity loss vs (what to date has been the gold standard for uberfast rifles) 26 inches or longer, at Z length of tube.
How many times have we read, both ere and on the gun rags, "the 264 WinMAg with a 22 inch barrel is just a loud 270" Seems to not be so! Or "better hold out for a 257WBY with a 26 inch barrel, the 24 inch tube on the Vanguard and Remington will not allow the 'ol Roy to do what it was designed to do"
What to make of all this is the million dollar question.
