how much of a pain in the ass is it, and what do I need?

Well-mounted 4" vise, armorer's wrench, upper reciever action block

a little know-how.

for what reason do you want to change your barrel?

If it is because you have fired the piss out of it I would suggest sending it to have it rebarreled if you have no experience or parts on-hand.


If you just want a change, keep the upper and buy another one;that is the best part of the ar-15, one day you may feel like shooting an m-4gery the next day a 20" full size.


By the time you purchase all of the parts such as barrel wrench, upper receiver block etc. you could have had it rebarreled by a professional or purchased a new one.


Just my .02

Not real hard.  Check this out.

Not that bad get a barrel wrench and a set of upper receiver blocks so you can hold it rock solid wich is needed to tourque it right,some disulfide or high temp grease for the receiver threads.and a set of pin punches and a hammer for the gas tube and a rubber malet wouldnt hurt as Bushmaster told me to hit the receiver from the rear onto the barrel indexing pin wich should fit snug.And if you have never done it before the armorer video from bushmaster.