The only safe method of upgrading the power of air rifles requires increasing the pellet velocity. Increasing pellet velocity improves the air rifle's ability to quickly and humanly kill a game animal. Upgrading the power of an air rifle by increasing the pellet's velocity also increases the point-blank range of the rifle and improves accuracy by flattening the ballistic arc. Fired from air rifles using the same pressure, lighter Performance Ballistic Alloy rifle performance pellets have greater velocity when compared to conventional pellets.
Shoot a five-round series using conventional pellets (use the paper bull's-eye target). This shot group will be used for comparison to confirm increased pellet muzzle velocity. Replace the first bull's-eye target with a new one and shoot a second five-round series using PBA rifle performance pellets (The bull's-eye centre is the point of aim in both five-round series). Compare the first bull's-eye target with this one to confirm an increase in pellet velocity--an increase in velocity will raise the location of the shot group on this bull's-eye target compared to the first target.
Place the stack of wet newspapers on the ground and fire a conventional pellet into the stack. Fire a PBA rifle performance pellet into a second stack of wet newspapers (Placed the same distance from the rifle as the first stack) so that you can compare the depth of penetration between the two different pellets. Peel back the wet newspapers from each stack and measure the depth of pellet penetration in each. The faster PBA pellet will penetrate deeper than the conventional pellet, confirming an increase in muzzle velocity and pellet energy
Place a block of ballistic gelatin 10 meters from the air rifle muzzle and fire a conventional pellet into the gelatin block. Replace the first gelatin block with a fresh gelatin block and fire a PBA pellet into it. Compare the pellet cavities formed in the two gelatin blocks to confirm that the PBA pellet is producing deeper penetration than the conventional pellet.
Re-sight the rifle when using lighter, faster PBA rifle performance pellets. You may be able to confirm an increase in pellet velocity by using a local shooting range's chronograph.
Do not make any modifications to the air rifle in an attempt to increase its pressure capabilities. Severe injury may result if the pressure chamber ruptures.