Check out S.I.R. mail order out of winipeg,I' m sure they can set you up. As for the 24" barrel, there are some guys using them on birds.From what I' ve read, they say the difference from 24 to 26 to28 is minimal.I found that a little strange,but thats what some have been saying[] Personally,I really don' t know, ask the guys at SIR maybe they can shed some insight.
Hope this helps, let me know