I was a bit concerned with taking a hacksaw to the barrel to fit the extension in case I cut in the wrong place or made a hash of it.
I seem to remember reading something around here that some people were using small pipe cutters, the kind that are designed for hobbyists who need to cut relatively small diameter plastic and/or metal tubing, apparently these make a nice clean cut that is square with the tubing, and it's also easy to cut the tubing in precisely the right spot. I doubt I would be able to do the same with a hacksaw....
