Anybody have experience with Colibri (powderless) rimfire ammo?

[tularetom]

My son lives in a neighborhood of smaller lots but he has problems with raccoons getting into his garbage cans and compost pile. He'd like to dispatch the boogers but he doesn't want to make a lot of noise and get the neighbors pissed off about somebody discharging a firearm in the hood.

Somebody suggested these subsonic .22 rounds to him. They have no powder but rely on primer to propel a bullet of about 30 grains at something like 500 fps. The advantage is that since they are moving at a rate less than the speed of sound they will not produce the loud report that occurs when using supersonic ammunition. They're supposed to be quieter than an air gun but based on the weight of the projectile and the relatively low velocity it seems unlikely that they would produce enough power for varmints. Sounds pretty wimpy to me.

I offered to let him use my .22 caliber pellet rifle that can push a 20 grain pellet at 1000+ fps but he wants to try these things.

Has anybody ever used this ammo? Know anybody who has?