Seems that the bradley issue troubles me a lot with all those versions and modifications.

CI was told the bradley can carry two different 25mm chain guns
What are the differences of the guns?

There are two different barrels for the 25mm Gun. One is the one that comes with most kits and the other is a fluted barrel, which is a bit shorter and has cuts in barrel, and from what I was told by a Bradely Master Gunner, those are there to case the barrel to shear off instead of bending the barrel if it hits tree or the like.

well i'm not a bradley crewman , but the only change that i have seen on the chain gun is the barrel . the old one is round and long , the new one is short and " fluted " it has groves cut into the barrel to create more surface that is exposed to the air to cool the barrel. mabey these pics will help.

good pm-i might be wrong but-the 25mm can fire regular rounds and DU rounds-each has to have a different barrel...DU is a hot round
carpe diem

It's been a while since I was on a Bradley, but I know nothing of two types of barrels. It's very possible that another has since been introduced, but as of the first Gulf War, we only had one barrel. The chain gun shoots HE, high explosive, or AP, armor piercing, rounds.
The barrel we used was long and smooth. Hope this helps.

The fluted barrel was introduced as one of the ODS modifications. Our scout platoon was going from the six M3A2 formation to the ten M1025/1026 HMMWV formation in the mid 90s, so I remember us not worrying about getting the newer barrels or not.