The AC-130U Spooky is replacing both the 25MM Gatling gun and the old and true 40MM Bofors canon with the 30MM Bushmaster. This is great news for the crews and very bad news for the evildoers. The 30MM has had great success with the Marines and is a great replacement for the USAF's older lead throwers. The 25MM in my opinion never lived up to its big brother's (the A-10's 30MM Gatling) reputation and the crews were having tons of problems with it (I recall a couple of times the gun had shot up #1 engine...never a good thing)
The 30MM will add accuracy and also a more maintenance friendly weapon.
The USAF and AFSOC plans to add the 30MM to the AC-130Hs as well with both aircraft being fully updated by 2010.
The AC-130U will also be adding the GBU-44 glide bomb on the outer hard points where the IRCM pods once were placed.
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