The easiest $25 I ever saved......
Turned out to be even easier than I hoped. The standard Contender hinge pin is just barely larger than the hole in an Armour Alloy barrel, it almost wants to go. You only need to remove around 1 thousandths, maybe 5 ten thousandths, or so. I wrapped some 400 grit 3M silica/carbide sandpaper around the shank of an old Philips screw driver. Rotated it a few times in the hole, then checked the fit of the hinge pin (rinse paper, repeat). The pin fit snuggly after about 30 turns. Polished it more than reamed it. All-in-all, it took about 3 minutes. -- Kernel