It depends on the the bullet weight you are using. The faster the velocity, the more velocity percentage-wise will be lost.
Generally speaking, you should loose about 20 fps per inch removed. Thus, if you are talking about a 22" barrel, and thus a 2" loss, you are talking about 40 fps slower.
Granted, I like shooting 24" barrels in this cartridge, but this is not a big deal. In fact, I own a Browning A-Bolt-I Stainless Stalker and it has a 22" barrel also. I haven't shot at long distances, but at target shots up to 200 yards, you really can't tell the difference.
Some people go as low as a 20" barrel on the .270, but 22" is the lowest I'd go.
Zachary