I know there is no exact definitive answer to this but just looking for a ballpark figure as I don’t have a lot of experience shooting 22. I’m curious on average how many fps slower 22 gr pellets shoot than 18.1 gr shot on the same tune ?
22 caliber pellet question?
- Thread starter Trucker3573
- Start date
There won’t be an average FPS loss. The physics aren’t linear in that way.
The simplest mathematical prediction we can make is if we assume the energy dumped by the valve is consistent for a tune. Thus we assume muzzle energy is constant regardless of projectile mass.
In that case assumed above, the FPS will be:
Square root(Muzzle Energy * 2 / (4.4421e-6 * Projectile Weight) = Muzzle Velocity
For a 25 FPE tune with an 18.1gr, you get 788 FPS.
The same tune with 22gr theoretically yields 715 fps. ( - 73 fps )
Again with 25.9gr gives 659 fps. ( -129 fps ) (( -56 fps ))
This suggests that heavier pellets are more efficient at picking up velocity. There are some complications, however:
Friction of the pellet in the bore may not be the same. Engraving force may not be the same. Skirts may have a more or less efficient seal depending on thickness. All of these can cost you speed.
So, the fps loss is going to depend on the starting muzzle energy of the tune and the qualities of the two pellets in the bore. Hope that helps.
The simplest mathematical prediction we can make is if we assume the energy dumped by the valve is consistent for a tune. Thus we assume muzzle energy is constant regardless of projectile mass.
In that case assumed above, the FPS will be:
Square root(Muzzle Energy * 2 / (4.4421e-6 * Projectile Weight) = Muzzle Velocity
For a 25 FPE tune with an 18.1gr, you get 788 FPS.
The same tune with 22gr theoretically yields 715 fps. ( - 73 fps )
Again with 25.9gr gives 659 fps. ( -129 fps ) (( -56 fps ))
This suggests that heavier pellets are more efficient at picking up velocity. There are some complications, however:
Friction of the pellet in the bore may not be the same. Engraving force may not be the same. Skirts may have a more or less efficient seal depending on thickness. All of these can cost you speed.
So, the fps loss is going to depend on the starting muzzle energy of the tune and the qualities of the two pellets in the bore. Hope that helps.
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Not sure in .22, but in .177 per 3.5gr it's an average 100fpes difference, and in .25 between 25.39 and 33.95 it's 100fps as well. In .22 I have found the difference between 18.13 and 15.89 is usually 40-50fps
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I am glad i do not find it necessary to know exactly what a pellet is doing . The only time i crony a gun is when i first own it . After that if i see a new pellet i try it out , if it works good then ill use it if it fails i give it to a friend to melt down . i like to keep air gunning simple '
buy / shoot / fun
buy / shoot / fun
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That is almost spot on figures that I get from my Stoeger Ranger w/18+ JTS vs 21+JTS pellets. Stellar accuracy w/ both. Many dead Ghogs agree
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I tried the AEA brand 18s & 22s in same rifle recently. While I can't remember exact velocity difference, I do remember affect. The 18s wanted slower velocity and the 22s wanted higher velocity. In other words, if you had a tune for the 18s, then the 22s were going too slow. And vice-versa for a tune with the 22s.
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I bet you are in the ballpark and your gun might even shoot them faster. Projectile weight also plays with how and how long your valve actuates. It's extremely nuanced. Buy a tin and try, even if they're slow you can use them for plinking at worst?
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