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Old 10-14-2012, 01:37 AM
mscampbell2734 mscampbell2734 is offline
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Quote:
Originally Posted by 125JHP View Post
OK, so for a given cartridge, bullet and gun does equal pressure equate to equal velocity regardless of the powder? In other words...
if it takes Xgr of powder A or YY gr of powder B to achieve 900 fps will both loads be generating the same pressure?
NO

Its not just pressure but PEAK pressure and pressure duration.

Think of it this way. The total energy put into/upon the bullet will determine its vel when it exits the muzzle.

If you load a extremely fast powder, lets say Bullseye, the powder builds to a rapid spike and then tapers as the bullet does down the barrel.

A slow powder, 296 for example, requires a heavy crimp because the powder actually begins to burn in the case and builds pressure for a micro second before the bullet exits the case. This pressure stays constant the entire time the bullet is in the barrel, and in fact a longer barrel allows more time for the pressure to act on the bullet. This is why longer barrels with MAGNUM loads give higher vel., think 20 inch rifle barrel vs. 6 inch handgun. Longer barrels with non magnum loads, think .45 ACP, give very little vel increase.
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