I have a 18" barrel on my rem 870. I bought a couple different chokes for it for birdhunting but I got to thinking, am I going to loose too much velocity out of a 18" barrel vs somthing like a 24 or 26" barrel? I hunt pheasant, grouse, rabbit and other small game. I want to be able to use my barrel for bird hunting and hd but I dont know if it will get the job done for hunting. What are your thoughts?