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Barrel length vs volocity

Started by slivershooter, June 16, 2014, 04:29:26 PM

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slivershooter

Hey guys, I have been otherwise occupied for some time and just now getten back to my AG's.  Got a question that maybe has been answered many times but I'll start a fresh thread here.  At what length does the length of a barrel become a drag on the pellet in a Co2 gun.  I can see that much is wadted on a short barrel and volocities are higher with a longer barrel, But there is a point that the psi's are dropping. ???
I am a Christian, I am an American. I support the 2d Amendment and I am proud of it.

breakfastchef

Larry

BillK

I  wonder if 18" is best why Crosman makes 24" barrels.  Seems if you have enough power the longer the better.
Makes me wonder.... ???
West Michigan
Crosman Nitro Venom .22
Crosman 760 - 782 - 1077
Sheridan S S - H - E9
Benjamin NP pistol - Disco - Prod
MIC B1 .177
2300S - 2300T - 2400kt
1740 - 2240 - 2250 - 1760 - 2260 - 1701P
1322 - 1377
MK I & II

T191032

Do some searching around here on the board, several of us had done some testing with various lengths. 
It ain't like it used to be but, eh, it's do.

breakfastchef

Quote from: BillK on June 16, 2014, 08:44:37 PM
I  wonder if 18" is best why Crosman makes 24" barrels.  Seems if you have enough power the longer the better.
Makes me wonder.... ???


Going to guess that after 18", there is no more additional expanding pressure from the initial blast of CO2 out of the valve, and the final 6" of barrel length adds drag to a non-accelerating pellet.
Larry

KevinP

Quote from: breakfastchef on June 16, 2014, 11:04:24 PM

Going to guess that after 18", there is no more additional expanding pressure from the initial blast of CO2 out of the valve, and the final 6" of barrel length adds drag to a non-accelerating pellet.

well said ...   :-*
Kevin
Albany, New York

BDS

Purrty-much... the gas expansion has a finite level (barrel length) given the small volume of co2 available.
Brian

BillK

#7
Perhaps .22 is different from .177 .  Back in Nov. 2013 Airriflenut was changing/checking barrels on his .177.  The 24" shot 703fps while the 18" shot 677fps. 
I guess I'll have to put an 18" barrel on my 2260 and see what the difference is.
Seems if the valve is low power than a longer barrel would/could slow down a pellet from the added friction of the longer barrel.  So, is a 2240 valve powerful enough for a 24" barrel?
This is getting above my ability to conceptionalize.
. :-[
West Michigan
Crosman Nitro Venom .22
Crosman 760 - 782 - 1077
Sheridan S S - H - E9
Benjamin NP pistol - Disco - Prod
MIC B1 .177
2300S - 2300T - 2400kt
1740 - 2240 - 2250 - 1760 - 2260 - 1701P
1322 - 1377
MK I & II

tinker

The best I ever got out shooting CO2 was a 724fps average out of a 24" .22 barrel shooting 14.3gr. pellets.  The rifle was bulk fed using a 9oz. bottle and an Archer tank block mounted with 4 screws.  The valve was a gas hog and I got just 6 shots out of a 12 gram cartridge.  Using a shorter barrel it couldn't break 700fps.  No I didn't get a hundred of shots either.   Not to efficient build.  The CO2 usage was too high for the fps I got.  I think I used a lot of the parts for my 1st Disco build!

Glen
(Tinker)
If it's not broken then modify it!

targettgii

Tinker I believe that those are the key words bulk fed or hpa.I think (my own opinion here)having not done any testing that a higher volume power supply would enhance the longer length barrel rather than hinder it.And with a 12 gram power supply you get so much power behind the pellet then that is it.
Tom

Modded 1377
Modded 2240
Modded 1322
1750 HPA pistol
Stock 2260(for now)
.22 Gen.2 Marauder
CCS 2300
Custom 1740
38 T

agninja

Perhaps the longer 24" barrel is for the sake of accuracy, if not additional power. Though I can't imagine there being much of an appreciable difference for either. With the 24" being simply too long and unwieldy for such a small platform, I would never get one anyway.
Black air pistols matter.

tinker

Yes the key was bulk fed Tom.  Even with the 24" barrel she spewed CO2 out the barrel just like a stock 2240 with a fresh cartridge with every shot! 
(Tinker)
If it's not broken then modify it!

slivershooter

Thanks for the input guys. I kinda had the feeling that at some point, longer barrel lengths would be a drag cause the UMFF is gone.
I am a Christian, I am an American. I support the 2d Amendment and I am proud of it.

targettgii

i was just saying what I was thinking like I said it was my opinion an untested one at that.
Tom

Modded 1377
Modded 2240
Modded 1322
1750 HPA pistol
Stock 2260(for now)
.22 Gen.2 Marauder
CCS 2300
Custom 1740
38 T

BDS

Tinker noted the key fundamentals with co2. It's a fine line between optimum velocity and shot count, especially with co2. With a nominal pressure of 830 psi regardless of volume, the amount of gas used per shot starts to become "waste" as a function of "filling" the longer barrel for each shot.

On barrel length vs. accuracy, many of the best quality airguns have 12" and 14" barrels and are one-hole shooters, (HW, FX, Air Force etc).
Brian