The launch pad will be a recent Vaquero, and there seems to be a rash of undersized cylinder throats in these, unfortunately.
That's not a bad situation!
This would be my plan:
-Lap the bore. Use a soft lead bullet, tap it down the barrel. Coat with fine oil and silicon carbide lapping compound (300 grit to start, then 400 and 600) and repeat the process. Some people do firelapping, where you shoot the carbide coated bullets, some do it by hand. Veral Smith, cast bullet guru of LBT fame, did the latter.
What you want is to smooth the bore and remove any choke at the barrel threads.
(One neat trick is to cast a lead bullet with a cleaning rod jag in the mold. You can then thread the slug to a cleaning rod to speed up the lapping.)
-Your barrel with now be .001"-.002" larger than when you started. Whatever the actual groove diameter, ream the cylinder throats .001" larger.
You'll need to buy or cast bullets to fit. Voila! Match grade accuracy to any range that a sixgun would be practically needed.
This process is very straightforward, and even with tool cost, is very cost effective.
Jim
PS: Beyond this, there are other factors such as your reloading dies. The resizing die and expanding plug need to work with your bullets and brass. Too many 45 Colt sizing dies are just 45 ACP dies with a different roll mark.
Regarding Jacketed Bullets: CH used to make a die to bump up a jacketed bullet by about .001"
They really worked. I saw this with a Veral Smith reworked Ruger Blackhawk.
