Thread: Barrel length
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Old 09-12-2006, 05:42 PM   #20 (permalink)
amcfall
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Join Date: May 2006

Quote:
Originally Posted by Schmitti View Post
man why am I always the engineer that steps up to the plate in these situations?

Okay looking at post barrel ball acceleration.... you basically have a vessel that is containing pressure (the ball and barrel) The size of the vessel is increasing at an increasing rate (acceleration of ball forward).. as the size of the vessel increases the pressure decreases... once the ball is free of the muzzle of the barrel you no longer have a contained vessel, so the pressure 0 (gauge), but you still have molucules of CO2, HPA (no longer hpa) moving/expanding in a linear manner for a short distance until they loose their energy (we see this as the "clouds" of CO2 on cold days)... Now because we have the ball free of the barrel (and friction) and there is still some energy acting on the ball from the gas continuing to expand then you may see some additional acceleration... but what ever you see will be nominal. I think a lot of companies may be marketing on this theory.. and not on anything measurable..mainly because it's easier to say it's happening and have the theory in your back pocket... than it is to show that it is happening (it would cost more than their marketing budget to prove what is happening in that 1/4" away from the muzzle of the barrel).

The science part, I'm pretty sure we can substantiate the theary, I know there are a few other physic geeks here that will probably agree with what I said... it's the actually physically proving of the "post barrel" acceleration that is damn near impossible due to lack of proper tools on my end.

E
Agreed. While not based on anything but my gut feeling I don't think that the uncontained (or unchanneled, maybe) energy will have any major effect on the ball. If anything I'd guess that the randomness of the expansion would mess up the accuracy if anything.

Of course,t he main reason I've never bought into that was how long would this effect last? Maybe an inch? How far out do you chrono? A foot? So by the time you're measiuring the velocity and tuning the gun the ball would have stopped accelerating (actually, it's just negative acceleration , but I digress).

Oh, and I like 12" barrels for aiming reasons. I've always kinda thought that a smooth tube is a smooth tube ( other than paint to barrel match). I have seen massive differences in consistency while matching paint, I've had cheap paint do +/-20 out of one barrel and +/- 10 out of another. Since I believe that consistency and paint are the two biggest factors in accuracy I think the "barrel match" crowd may actually be on to something. Of course, IIRC one day I had better consistency with a 'bad' paint to barrel match (loose) versus the tight fit so I went with the loose fit, better consistency with a little efficiency hit.

Avery

Avery
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