I have noticed pcp rifles with barrels as short as 10 inches while other are over 20. I know that in 22 LR pistols, sealed breech aka non revolvers, have a reduced velocity compared to rifles and anything much over 18 inches and you begin to loose velocity. What are the optimum or most efficient barrel lengths for different pcp muzzle velocities such as 700, 800 and 900 fps. Also what effect does barrel length have on accuracy in pcp rifles, all other things being equal?
- The AGN App is ready! Search "Airgun Nation" in your App store. To compliment this new tech we've assigned the "Threads" Feed & "Dark" Mode. To revert back click HERE.
Optimal Barrel Length
- Thread starter Dan25
- Start date
It works pretty much the same for air guns as it does for PB. When the valve is opened highly compresses gas (air) expands rapidly pushing the projectile ahead of it. If the barrel is to short you lose efficiency (some potential is lost) if its to long then bore drag will begin to slow the pellet after maximum expansion has been reached.
If you want a short carbine length gun then you are willing to give up some velocity. Want a high power gun with maximum velocity then you need a longer barrel. Thats why the bull pup designs are so popular. Short over all length with a long barrel. Gun designers do try to balance barrel length with power output to maximize efficiency, if a gun is to be variable power then compromises have to be made usually on the lower settings.
As far accuracy goes barrel length has little to do with accuracy, as long as the projectile leaves the barrel cleanly with the proper rate of spin at the proper velocity it should be good to go. Barrel length mainly determines velocity not accuracy.
Hope that helps.
If you want a short carbine length gun then you are willing to give up some velocity. Want a high power gun with maximum velocity then you need a longer barrel. Thats why the bull pup designs are so popular. Short over all length with a long barrel. Gun designers do try to balance barrel length with power output to maximize efficiency, if a gun is to be variable power then compromises have to be made usually on the lower settings.
As far accuracy goes barrel length has little to do with accuracy, as long as the projectile leaves the barrel cleanly with the proper rate of spin at the proper velocity it should be good to go. Barrel length mainly determines velocity not accuracy.
Hope that helps.
Upvote 0
Yes that was a good answer 30 Cal but not exactly what I was curious about. The info I was seeking was at a given pcp velocity range of 700 to 1000 fps at what point does barrel length, as in longer, begin to have a negative effect on muzzle velocity? I know that at some point as pressure begins to drop frictional losses will result in a lower muzzle velocity than if the barrel were a few inches shorter. I guess only industry insiders would be the best source of this type of data.
I know there are other design variables like making the bbl. short enough to allow for a Marauder type shroud to be fitted without making the gun excessively long. What got me to thinking was the 100 fps increase in muzzle velocity on the Hatsan AT 44 Long over the Short version.
I know there are other design variables like making the bbl. short enough to allow for a Marauder type shroud to be fitted without making the gun excessively long. What got me to thinking was the 100 fps increase in muzzle velocity on the Hatsan AT 44 Long over the Short version.
Upvote 0
Lots of variables to consider. A lot depends on valve flow characteristics and dwell. A setup that can deliver a given velocity with short dwell will favor a shorter barrel for that velocity and vice versa.
Upvote 0
Springers, 10-14" is about max fps.
PCP rig's IF you are trying to make power -even 20fpe but esp. for HIGH power rigs, and, non-regulated rigs- 30" would not be too long. When changing a barrel most pcp folks are looking at 10+fps per inch added if no other tuning is done. Naturally this may not apply if you are shooting say 3.9fpe but anything from a discovery on up use the 10-15fps per inch added up to about as long as one can find. I picked up 50fps by putting a 25" HW barrel on a Bam50.
John
PCP rig's IF you are trying to make power -even 20fpe but esp. for HIGH power rigs, and, non-regulated rigs- 30" would not be too long. When changing a barrel most pcp folks are looking at 10+fps per inch added if no other tuning is done. Naturally this may not apply if you are shooting say 3.9fpe but anything from a discovery on up use the 10-15fps per inch added up to about as long as one can find. I picked up 50fps by putting a 25" HW barrel on a Bam50.
John
Upvote 0
Yes and what pellet weight? So many variables. If you tuned it for a specific velocity for a specific pellet at optimum efficiency it would only be optimum for that one pellet.
Upvote 0
Upvote 0
Thanks for taking the time to reply. It seems you have been down the long bbl. road a while back. If longer is better it would seem the bull pup is the way to go.
Upvote 0