How fast will my pellet go? (Need a math guy here)

[DarkRattle]

So right now my P-ROD is chrony'd at 700 FPS with 14.3 grain crosman premier hollow points after my tuning. I switched the 21.12 grain beeman kodiac copper plated (great accuracy and insane energy) and haven't looked back. The thing I wana know is if I'm shooting 700 fps with 14.3 grain, how fast am I shooting with 21.12 grain? I'm guessing 650 fps but I'm not sure. I don't have the chrony anymore so if any math guy can calculate and estimation, that would be awesome. 

 

[Marksman3006]

probably around 575 fps.

 

[DarkRattle]

"Marksman3006"probably around 575 fps.

ya I've been thinking around 600ish 

 

[bill_dd97]

About 575.

http://www.airgunsofarizona.com/energycalc.htm?energy=15.56&grains=21.12

 

[DarkRattle]

"bill_dd97"About 575.

http://www.airgunsofarizona.com/energycalc.htm?energy=15.56&grains=21.12

that's taking the fact that my 700 fps pellet is a lighter pellet giving me 15.5 FPE, wouldn't a slower pellet yet heavier generate more FPE?