Private Joker,
I have purchased all my Aguila ammo at gunshows or through internet sites. I have not seen it at any local retail or gun stores. The cases are the same length as Long Rifles (The SSS Sniper Subsonics use a .22 short case). The Colibri's are very quiet about the same or even less than my Daisy Red Ryder. I mainly use them in my Marlin 39A but have used them in the 10/22 as well. Only downside, other than manual cycle, is the last round usually nose dives in the mag and does not feed. The other 9 are no problem.
Sundog,
I have used these Colbri's in a PT22, Ruger MK II, and my Ciener 92FS conversion. Again no problems with feeding - just need to manually cycle every time.