Quote:
Originally Posted by marxman
If by net muzzle pressure you mean average barrel pressure I don’t know why you call it muzzle pressure. But I know from pistol carbine rounds if you load powders of different burn rates to the same velocity the slower powder will require a bigger charge and has more report because of the higher muzzle pressure even for the same speed. Of course the bigger charge has produced more gas for the same barrel volume it’s a bigger bang at the muzzle without producing higher velocity. For some reason the faster charge has accelerated the bullet more efficiently and the higher muzzle pressure of the bigger slower charge means wasted energy not more velocity in this instance
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As to your pistol carbine powder, the slower powder usually does require a larger charge will require more dwell time in a barrel than will the faster powder. Extend the barrel length a bit and the difference in velocity will become obvious.
Average barrel pressure is not muzzle or exit (net) pressure . I guess that's why its sometimes called exit pressure. I maintain that one can use projected exit pressure to measure muzzle velocity by simply using the net, or exit pressure projections taken at the muzzle just prior to bullet exit. It is equal to, and more consistent than you can get using peak pressure as a MV indicator. Peak pressure is listed in manuals as a guideline regarding safe pressures. That was mentioned, and equal muzzle pressure provides equal muzzle velocity.. that's all I said, but we have been using peak pressures for ever, haven't we ? I wasn't suggesting anyone use exit pressure, it's just a better indicator of MV.. in my opinion. The problem arose on this topic because I didn't mention what area the pressure was measured at when I first posted about equal pressure and equal velocity. Maybe you guys can ease up a bit now.
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