Don't do it.
Basically if it doesn't say, short on the gun or says longrifle only...you have your answer.
You run the risk of the following:
When you fire the round, the case expands. A short round in a long rifle chamber will expand in the middle of the chamber, continued use will not just put a fouling ring but grind an indent in your chamber. This ring may cause trouble with extraction of cases that are longer than the "short round" you are firing, it may "cant" your cartridge in the chamber and decrease accuracy over the life of the gun.
The jump from the chamber to the rifiling will decrease accuracy (despite claims to the contrary) as well will increase leading and impact wear to the throat of the rifiling. This will inturn decrease your accuracy potential when going back to the regular ammo.
I have tried CB longs, whos case is the length of the long rifle round and they work OK but they are not accurate enough for me.
If you really want quiet and live in a state that allows it, get a suppressor...more fun with a CZ can not be had.