For comparison, subsonic 300 BLK has about the same energy as 45ACP and no one says 45ACP is under-powered for self defense. Yes, in general supersonic rifle rounds wound better than subsonic pistol rounds, but when you get close to the upper edge of pistol and lower edge of rifle (like 300 BLK does), the differences aren't huge at home defense distances. As long as you're using the right round for the right purpose, it's going to work out OK. The opposite is true for all of these in the case of subsonic flow. Velocity decreases if a flow is heated externally. Velocity decreases along a pipe with friction. So, if we compare a designed-supersonic projectile traveling at supersonic speeds to a designed-subsonic projectile traveling at subsonic speeds, the results are real damned close on penetration, over-penetration, expansion diameter, etc. It is well known that once the flow of a gas becomes supersonic, it behaves very differently to subsonic flow: Velocity increases as flow area increases. A supersonic flow that is turned while there is an increase in flow area is also isentropic. The generation of sound waves is an isentropic process. When the change in flow variables is small and gradual, isentropic flows occur. A few of them will be designed to expand at subsonic speed (Hornady Sub-X comes to mind, some Maker stuff, some Lehigh stuff). Isentropic is the combination of the Greek word 'iso' (which means - same) and entropy. Almost all of them will have minimum expansion velocities that are supersonic. The manufacturer will say how fast their product has to be traveling to expand properly. Where people get caught up/turned around on this one is that they compare expanding projectiles meant only for supersonic use in both supersonic and subsonic use.
0 kommentar(er)
