Bean Bag Round Pressures

NeoBlackdog

July 02, 2011 06:06

Does anyone know what kind of pressure is generated by a 12 guage bean bag round at 280 FPS?

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  beantownshootah

  July 02, 2011 07:18

  Insufficient information to answer the question.
  
  Assuming we know the projectile mass (which is probably 40 grams), in order to calculate the PRESSURE (force per unit area) of the projectile on impact, we'd need to know the surface area of contact on impact, as well as the DURATION of the impact (which is going to depend on the elasticity of the struck surface and projectile).
  
  Put differently, if you were to fire a steel 40 ground ball against a brick wall, the peak pressure (PSI) will be a lot higher than if you fire the exact same weight 40 gram soft beanbag at the same velocity against a person with a 2" layer of clothes and soft abdominal fat.
  The beanbag will spread out on impact, increasing its surface area and decreasing the pressure (pounds/square inch), and the soft surfaces will slow down the impact, again reducing peak pressure.
  
  Perhaps you're asking the wrong question.
  
  Converting the typical 40 gram beanbag into English units, we get 40 grams = 0.0882 lbs.
  
  At 280 feet/sec your 0.0882 lb beanbag will generate 107.5 ft-lbs of kinetic energy (or 145.7 Joules) and 0.7674 ft-lb/s momentum.
  
  As something of a "ball park" comparision, a pitched standard 5 ounce baseball in a 90 mph fastball will generate 84.6 ft lbs (114.7 Joules), and 1.282 ft-lb/s momentum.

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  spas12

  July 02, 2011 10:33

  If you do mean pressure do you mean pressure on impact or chamber pressure, I can't tell you either number but, they should both be relatively low.

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  NeoBlackdog

  July 03, 2011 04:35

  Sorry guys, should have been clearer. I would like to know the operating pressure in the chamber/barrel, not the impact pressure of the projectile.
  Thanks

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