Difference between .177 and .22 Huma regs for FX

[hasenpfeffer]

Huma offers their FX regulator in .177 and .22, and possibly other calibers. I think all the air tubes are the same diameter, so what's the difference? I'm guessing it's the length of the spacer, so the larger caliber reg gives up a bit of cylinder capacity to gain a larger per-shot air volume. If that's the case, is there any reason (besides air capacity) that I wouldn't want to use a .22 reg in a .177 Cyclone?

 

[DaBinChe]

Just as you said, length of tube is longer in the larger caliber. For a while I used a .25 Huma reg in a .22 M-rod. If you are not gonna use that much power then go with the shorter one the longer one will give your smaller caliber more power. For example if I wanted to go down to 12fpe in my .22 then I would rather use the .177 reg so I can have a larger reservoir capacity, but if want to go max power while still regulated then I would use a .25 reg