If you are only shooting that slow speeds then probably a 4.7" Huggett Belita would be enough and if you need super quiet maybe a 5" Mini Magna that has similar sound reduction as the standard Snipe.
Which gun and more importantly how long is the barrel? Most likely you just need a tanto or belita........granted I use an emperor on my PP750 shooting at 650 FPS. i say go small or go big, skip the middle! Hahahaha
At low speed and in the .22 caliber (less report than .25) are you sure you even want one ? Depends on the gun of course, and on your purpose. Some shrouded guns become very quiet simply by inserting a few baffles or hair curlers, just one of those could be plenty for you.
Am happy with a Hatsan Flash .25. It is for hunting mongoose and rats. I have the 10 baffle on ebay coming in Sat., but think I would be happier with a short can. The two suppressors mentioned are about 2" shorter than stock.
Huma takes the cake. It's super light (in 30mm), super effective, and adjustable. I've got 4 of them and another one in 40mm if that tells you anything.
Simply for this reason... If you find you can use less moderator, you can simply make it shorter. The one in my fx crown is under 4" and is silly quiet because of some mods I did to the shroud behind the moderator.
If you need more, add more. It is either equally or slightly more effective than any of its competition, while also being extremely light. I don't know why anyone would get anything else to be honest.