MV AND BARREL LENGTH

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  • Last Post 12 July 2018
joeb33050 posted this 07 July 2018

Based on some limited data, it looks like MV decreases about .9%, (of the larger MV), per inch. Call it 1%, then from a 24" bbl at 1800 fps, a 20" bbl  MV would be 1800 - (18 X 4) = 1728 fps.

 

 

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joeb33050 posted this 07 July 2018

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sqlbullet posted this 10 July 2018

Ballistics by the inch has some good source data on this...

And a quick analysis there confirms what I expected.  This is going to be geometric, not linear. They log datapoints at 18, 16, 14, 12, 10, 8, 6, 5, 4, and 3 inches in 223. And the data does show a geometric relationship between barrel length and velocity.

 

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joeb33050 posted this 11 July 2018

The BBTI data covers 223 Rem bbl lengths from 3" to 18", see below:

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joeb33050 posted this 11 July 2018

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joeb33050 posted this 11 July 2018

I don't know what a "geometric" relationship is. The bbti graph looks like an exponential relationship, such as capacitor charge E vs. time, or diminishing marginal returns, (economics). Example below:

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joeb33050 posted this 11 July 2018

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joeb33050 posted this 11 July 2018

In any case, the relationship is pretty linear above 10" bbl length, and estimates using my data are PROBABLY reasonable.

Below 10" is uncommon. The relationship is probably kinda parabolic since mv starts to drop at some bbl length, maybe 6' or so.

Thanks;

joe b.

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sqlbullet posted this 12 July 2018

Agreed...Exponential.  Brain fart.

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