What are those??
Matt
Those are subsonic rounds that are for your .22LR. The ones I have are the Remington CBs. I believe the velocity is something like 740FPS or something like that, but the big selling point is noise reduction - you don't hear the crack like a regular rimfire round (1000FPS and over). It's more like a muffled pop.
For the squirrel in question - I had no idea at the time that the Recon was such a weak gun - obviously the marketing specs are just a little wee off. That's where a chrony always helps.
I'd say that probably the most powerful gun you can get under 500FPS for shooting squirrels is the Crosman Phantom .22 CAL version. That lists as 495FPS and when I chronied mine, it was around 465-470FPS. Still, at .22 CAL, it hits harder and has better energy transfer than a .177. I still can't say that I would have humanely dispatched that squirrel, but it probably would have been a better choice at the time (though I didn't own the Phantom then).
Some of the airgun hunting forums in the U.S. have minimum recommendations for FPS for things like squirrels and rabbits. I have heard minimums anywhere between 600 - 850FPS. But as several have intimated, shot placement is more paramount than anything else - you can have a 1200FPS air rifle and can't shoot beans with it (figuratively speaking).
Anyhow, it's getting late and my kids are having a hard time sleeping, so I should run...but I should leave you with something you may or may not have seen...this is a new offering from Gamo which looks promising - a 10-shot 88g CO2 powered pump-action (I mean pump like shotgun pump, not pump full of air) repeating air rifle. The video clip is a bit on the cheesy side, but you get the idea of how airguns have developed over time... My local gunshop will get these in May.
http://www.youtube.com/watch?v=2MTO1PbTSQE