Unfortunately, it's not well labeled to reflect this on the packaging. I know distributor sites often have "pistol only" warnings on these.

I did a little learning myself. I've only ever shot Colibri's, which are a ~375fps load, but there's also a "Super Colibri" that Big Uncle mentioned, that's a 590fps load. Assuming that just means a bit extra primer compound.

Really brings it down to about the same level as a BB gun (which are often 17-20grn at 300-700fps), but with the added complication that they are plugged bores waiting to happen.