As we all know, airgun manufacturers often use velocity as a marketing trick to create illusion about power. Sending 4,7gr Gamo Platinum pellet around 1200fps generates only 20 Joules of energy from the muzzle and half of it is lost after 20 meters due to high drag that skirted pellets create, especially in high velocities. I’m not saying that PCP airguns aren’t powerful – they are (as you can see from the graph below). And well, power is relative subject. Any gun compared to .50BMG is a peashooter.. and “fifty” is nothing compared to M61 Vulcan.
For comparison, I’ve taken some common handgun cartridges and averaged numbers from available cartridges (didn’t include +P ammunition). From airgun camp, I took only factory build guns. By tuning and tweaking, one can easily achieve +20% more power from almost any PCP airgun. There is also some custom build air-rifles, which can achieve insane power levels past 4000J, which is equivalent to .30-06 centerfire cartridge.
Another approach to measure power is momentum of the projectile. While measuring in kinetic-energy favors velocity of the projectile, momentum does not. For the chart below, I chose airgun bullets/pellets to be a bit on the heavy side for the given kinetic energy in chart above. Things look bit different now. Notice how .50cal Sam Yang gives almost the same “Umph” as 9mm and .45cal Texan with it’s heavy 350gr bullet has much more momentum than regular 230gr .45ACP ammo. Of course this is highly dependent from the selected bullet weight, but it gives you the idea, right.