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Old August 7, 2012, 01:28 PM   #1
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Join Date: February 18, 2009
Location: SE Michigan
Posts: 462
Question about the "Shockwave" and short barrels

I got to thinking about the shockwave that occurs upon firing and I'm under the impression that it's about 18,000 fps. So I measure the barrels on my 22 3/8" .204, 16" .223 AR15, and 20" on my .243. I subtracted a cartridge length from each, divided that length by the fps I get from those loads, and deterimined the amount of time each bullet is in the barrel. Then I divided that length by 18,000 fps to determine one trip in the barrel. When I divide the shockwave time into the time the bullet spends in the barrel, I came up the the amount of times it would go back and force until the bullet exited the muzzle and found the following:

22 3/8" .204 Ruger - 6.64 times

20" .243 Winchester - 5.46 times

16" .223 Remington AR15 - 7.2 times.

The 16" .223 has the shortest barrel as well as the lowest velocity but it would seem to me it would be the hardest of the 3 to find a suitable load where the shockwave is closer to the breech rather than nearer the muzzle, since it's making more trips back and forth. Does this sound reasonable?
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