Inevitably, KelTec’s new .22 Magnum (WMR) chambered PMR30 pistol will be compared to the FN FiveseveN pistol which fires the ballistically similar 5.7x28mm cartridge. If people are not saying it now, they will be soon saying that the .22 Magnum is the same as the 5.7x28mm. I used to say the same thing. It turns out that this is far from the truth.
KelTec have stated [PDF Link] that a 40 grain .22 WMR round should reach a velocity of 1230 fps from the 4.3″ barrel of their PMR30 pistol. This works out to 134.40 ft/lbs of energy.
This is a significantly less than the FN FiveseveN USG (4.75″ barrel), which can push a 40 grain bullet at 2009 fps. This works out to 358.57 ft/lbs! Nearly three times as powerful as the .22 WMR! ^{1}
This does not mean that the .22 WMR is not a good cartridge. It simply means that the 5.7mm is optimized to be fired from a pistol, rather than the slower burning .22 WMR loads which are designed to be fired from a rifle.
UPDATE: Added correct link to specs on KelTec’s website : http://www.kelteccnc.com/downloads/SHOT2010_preview_keltec_PMR30.pdf [PDF Link]

I assume that the 5.8mm load mentioned above it a hot load. I also assume that KelTec will be publishing the results of the best performing ammunition they could find ↩
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