Well looks like I'm typing this for a 2nd time. Ugh.
Here's what I did:
-Took the barrel out of my Star PD. There was leading for about 1/8" ahead of the chamber, about 3/4 the depth of the rifling (which itself is rather shallow)
- Plugged the chamber with a spent casing placed inside two "fold and close" baggies to give a tight seal (best I could come up with)
- covered the barrel with another bag and rubber banded on, to protect bluing (found out this was not needed later when some fresh solution got on the barrel and did nothing to the finish)
-mixed (by eye) 50/50 store brand white vinegar and hydrogen peroxide.
- added enough solution to cover the leading, about 1/4"
-Watched with a light, saw bubbling and cloudiness by the lead, bare steel had no signs of reaction what so ever.
- waited 20-30 seconds and dumped out, running dry patches down the barrel followed by some Ed's Red to clean out whatever solution & crud was still in there.
(this was out of an abundance of caution, as the barrel wouldn't be that easy to replace if I damaged it)
-repeated 3x
-Each time a black smudge would come out on the first tight dry patch through the bore.
- All the lead is gone, the bore is bright and shiny with no signs of pitting or discoloration.
Interesting point: This seems to work better on the lead in the bore than it did on a sliver I cut off a cast boolit. The reaction the the bore was almost immediate, the sliver of hard lead took about a minute to start reacting.
This is not something I would use on a S&W registered magnum or a collector Luger (or anything that cant be replaced) JUST in case something were to go horribly wrong, or even use every day on most guns as I'm don't think repeated use of even a weak acid in a barrel will do it much good with heavy use. But for occasional difficult lead it seems to work well, and fast.
Other people have mentioned and I will too, be careful of the byproducts of this process. It results in lead acetate, which is easily absorbed into the body and much more toxic than pure lead. Wear Gloves! It also has a sweat flavor (Romans used acid in lead containers to make a sweat drink) so as appealing as it may seem, don't go adding it to your morning coffee
YMMV.