As someone who is aspiring to just do anough smithing to work on some of his own guns in SOME area's (1911 triggers and most others will ALWAYS be left to a real smith, although I did follow a bit of stuff from a Beretta factory guy on improving the trigger of a U22 neos and I went very slowly and instead of removing material just did some light polishing and it worked, I wasn't aiming to really lighten the trigger, just smooth it up for a better feeling and lighten by maybe .2 ounce, and was successful, it's a completely different type of sear), this throat job is something I may consider doing some day if needed. So it brings me to a question about it.
In order to do such a job, the best idea in my opinion would be to carefully match the angle of the feed on the barrel as best as possible, and go extremely slowly and check fit often until you are close to eliminating the the discrepancy between the barrel and throat. Then take care of the feather of the edges on the left and right, then finish up by hand polishing very slowly and carefully until the throat lines up perfectly with the barrel. This would be my take, and I would like to know how correct I am in this? Also if the procedure is correct but the angle matching is not that would be beneficial as well.
I see this type of thing as only needing to be done if you need dead reliability of feeding of hollowpoint ammo. If you are having feed problems with ball ammo you may have other area's that need to be addressed. Also something comes to mind to check first if you are having feeding problems. Does the read of the barrel lift up creating a gap for the round to get caught on between the barrel ramp and the throat? Would this also be something more likely to cause feeding problems? The reason I bring this up is I had an old Tokarev 213 pistol that had some feeding and extraction problems caused by a heavily worn barrel. The extraction problem was obvious, the casings were getting blown out into a bowl shape, and hence getting stuck in the chamber(new barrel was being imported but got delayed so long by customs I gave up and got rid of the gun), and also with careful examination it was noticed the barrel lifted at the rear, causing the lip of a hollow opint round to occasionally get stuck on it, and deform the lip of the round with a nice little divot or slice depending upon your point of view.
Rev. Michael