Originally Posted By: SqueezeThere are more factors than just barrel length contributing to velocity, so there is no easy answer here. Longer barrels typically show increases in velocity, than shorter barrels, but one would probably have to buy a long barrel and start cutting off chunks to know for sure. The one ARP barrel I have studied the most, chronographs 95 Gr. TTSX bullets, over Alliant RL-7, at an average of ~2850 FPS MV. Since I am not seeing signs of pressure, I probably could squeeze more out of it, but I stopped when I hit .5 MOA, and no signs of pressure. I started to grow groups sizes above my charge weight, and retreated when I did see hints of ejector prints, on the case heads. I don't chase speed, but itty bitty groups hurt my face from grinning. And given what I saw on the whitetail autopsy, I don't need more velocity. A 2" exit, with a 4" channel of ground bone and tissue under the hide, told me there was plenty of energy at that speed.
Squeeze
Good points Squeeze. Years ago, an old gun-writer actually did take a rifle with a 24" barrel and chronographed a bunch of different loads. Then he cut and crowned it an inch shorter and repeated the testing. His results showed exactly what I have been telling customers for years. That is there is no "formula" for velocity loss "per inch". His findings were all over the board, and if you have QuickLoad, you can see why. Every powder has a different pressure-curve. Where you cut the barrel with respect to that curve is going to dictate what you will lose for velocity.
He also found that it was not linear. That also makes perfect sense, because again, you are cutting into a curve that isn't linear by any means. You may start out by loosing 50 FPS/inch, but at some point, that number is going to start to climb rapidly, as you cut into the high-pressure part of the burning curve.
Bore diameter VS. case capacity will tell you a lot. Small bore, moderate case capacity = long barrel. Large bore, moderate case capacity = short barrel.
