Longer barrel

[leadslinger22]

Well physics got me thinking the other day and i simply cant put an answer to it. The question i was wondering about is if u have a cannon ball in a cannon with a 4 ft barrel and a cannonball in a cannon with 6 ft barrel in theory the ball in the 6 ft cannon should launch farther because the air from the explosion pushes on the ball longer. Could this apply to airguns and if so why dont companys make longer barrels for their gun for that extra velocity? So i basically want to know if i put a longer barrel on my airgun would the velocity increase. Thanks

[gamo2hammerli]

No it probably won`t increase due to the extra friction.  Somewhere...someone...... tested the most efficient length of a spring piston air rifle....and the best length comes out to be around 12 to 14 inches.   Most think the extra length of the barrel is to make it easier to break the barrel....and maybe more pleasing to the eye(?).   In a PCP air rifle....a longer barrel will shoot the pellet faster than a shorter barrel....and even then, if you use a very very long barrel...I would think the velocity would suffer.

[leadslinger22]

Alright thats what i was thinking. Thanks

[SDale]

But it's true to a certain extent for HPA or CO2. The longer the barrel, the longer the Expanding gas has to act on the pellet.

[normal]

If it were as simple as all that, a zero length barrel would do the job, but it ain't.  Friction is a factor and so is available energy in the expanding gasses.  For each combination, there is an optimum length.  I can tell you that, with my 1377 and 2240 based guns, I get the most velocity with the maximum available 24" barrels.  As mild as these are, it's pretty likely that almost any air gun will benefit from greater barrel length.  Up to a point.

[Mark 611]

Right ! you only need 10'' barrel on a spring gun anything after that slows the pellet down, co2 or propellent of some type can take advantage of a longer barrel to accelerate the projectile this doesn't apply to spring piston rifles.

[spysir]

or is this a gas powered airgun?

  fps increase/decrease regarding barrel length, naturally your results just might vary and as it is a bit easier to make a barrel shorter than longer that is how the numbers run.
This is for a .177 using 850psi hpa.
21" barrel 814fps
20" 813
19" 804
18" 801
17" 781
16" 766
15" 747
14" 738


 John

[Bogey]

Question...will putting a longer barrel on my airgun  increase the velocity?   Maybe, up to a point.

I personally prefer shortened barrels 12 to 14 inch lengths .  They are handier for me,  I don't care for long barreled rifles.  Carbines are what I like.   Also, I believe the shorter barrels are stiffer.  And just as accurate as the long barrels.

[Mark 611]

well PSI as you've noted pounds persquare inch is some sort of pressure, not sure but I'd guess its not spring powered or would more likely be feet persecond.

[Mark 611]

What are you looking for in a spring powered cannon?

[howie1a]

On a springer the shorter barrel lets the pellet get out faster so that reduces the effect of the double recoil thus reducing hold sensitive , I have cut down a few air rifle ( springers) and found after recrowning them they shot more accurate and were less hold sensitive. Also I agree the longer barrel is more for making a break barrel rifle eayser to cock and is also for looks.  Howie

[RedFeather]

Black powder shooters have fiddled around with this and it seems that you don't get any gains over 42". At that point, velocity drops per inch. They also cut down to see when velocity would hit an unacceptable range. On the Dianawerk, someone mentioned testing springers by cutting the barrels and found that most began losing under 13". Once you go below that, break barrels can become a *(&(% to cock, too. Then guys add a muzzle brake and it's long, agan, but w/o the friction. One other thing you gain with a longer barrel is a greater sight plane if shooting with iron sights. Less parallax.