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  #21  
Old 05-28-2017, 02:07 PM
Alex Alex is offline
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Default A number of years ago...

... Mike Martin published some work in Precision Shooter about the relation of the powder used and the effect on barrel length. He did a pretty deep study and found that if you keep the chamber pressures the same, no matter what the barrel length change was, the powder that gave the highest velocity remained the same despite changes in the barrel length.

With some of the more modern powders and newer methods of measuring the full pressure curve, this argument is a little difficult to explain, as some of the slower powers give a flatter powder/pressure curve, something that is difficult to refute based on pretty simple high school physics.

However, as an academic friend of mine said, "empirical data trumps theory ever time."

Alex
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  #22  
Old 05-28-2017, 02:22 PM
moorepower moorepower is offline
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Quote:
Originally Posted by coyotezapper View Post
Just as a reference point QL shows that a 221 FB, 40 vmax, IMR 4227 ( which shows to be an optimum powder for this combo ), 20" bbl running at 3275 will burn 95% of the powder at just past the 14" mark in the barrel.
That's a powder I don't have, yet. I have A1680, H CFE BLK, RL7, H4198, H322and Lil Gun that should be close. CFE BLK is going to be the first one to test that I have. I would be happy with 3200+. How well does 4227 meter?
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  #23  
Old 05-28-2017, 04:48 PM
coyotezapper coyotezapper is offline
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Quote:
Originally Posted by Alex View Post
... Mike Martin published some work in Precision Shooter about the relation of the powder used and the effect on barrel length. He did a pretty deep study and found that if you keep the chamber pressures the same, no matter what the barrel length change was, the powder that gave the highest velocity remained the same despite changes in the barrel length.

With some of the more modern powders and newer methods of measuring the full pressure curve, this argument is a little difficult to explain, as some of the slower powers give a flatter powder/pressure curve, something that is difficult to refute based on pretty simple high school physics.

However, as an academic friend of mine said, "empirical data trumps theory ever time."

Alex
As I understand it, and I may be wrong it is all dependent on burn rate properties. Slower powders pressure curves are flatter and maintain pressures longer resulting in higher velocities without the initial over pressuring. Its not that faster powders can't reach these velocities, its the initial pressure max that occurs in the first few inches of burn that results in higher peak pressures or over pressure where faster powders suffer.

I hope this makes sense.
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  #24  
Old 05-29-2017, 01:02 AM
rrwildlife rrwildlife is offline
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Try a Nomex sleeve over the suppressor to reduce the heat mirage off the can. Suppressor heat up fast and the mirage it causes will deteriorate your accuracy. Same principle as using a heat shield on the barrel of a short range benchrest gun.

Hope this helps

Ryan
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