I don't believe barrels are "designed" for use with a particular load (like buckshot) but every one I have owned or used shot the best patterns with cylinder bore barrels. Running buckshot through any kind of choke restriction isn't going to help. I don't really care why. Just get a cylinder bore barrel for your 870 if you want to use buckshot and slugs. Or buy a longer barrel and cut the choke off of it. You cannot really expect tight patterns with buckshot at 40 yards either, especially with a choke. (Flite control or not)
Last edited by drail; October 21, 2012 at 08:26 AM.