Actual velocity of 495fps .22 rifle?

[FrickinChicken]

So I bought a nitro venom dusk .22 cal rated at 495 fps. I know they sell this in .177 as well. My question is do they modify the .22 version so it too shoots alloy pellets at 495, or is it the same exact piston in both models? Also, if it DOES shoot alloy pellets at 495 fps, how fast would it shoot 14.3 grain lead pellets?

Thanks!