Originally Posted by dodgerider

Ok I have a really bad noob question but I got to ask it . All I hear about smithing is color, engraving, and fixing, almost nothing about "custom guns". So my question is just how custom is custom like can they build a pistol from the ground up? Say I wanted to swap from a 4.9 barrel to a 5" barrel with high quality rifling job done on it. Then say I wanted the whole gun "tuned up" all the tolerances check and tightened. Can they do trigger tolerance tuning as well so it does not move as much and can I have it made to a shorter pull? Thks for any help.

Barrels:
Nowadays only specialty-barrel makers make replacement barrels. It's not really a modern gunsmith's job. The 'smith buys the barrel from a barrel maker, and fits it to your gun. Therefore, custom-made and custom-fitted barrels are just not available for some pistols.
However, all barrels can be relined by a 'smith. He drills-out the old rifling and solders or epoxies a new rifled tube into the hole. This probably could be done for some thick-barrelled pistols. Or, more commonly, the 'smith cuts off most of the old barrel, drills-out the remaining stub, and fits, and solders or epoxies, a whole new barrel that has been turned down at one end to fit into the drilled-out stub.
Sometimes, especially in 1911s and its clones, the part of the barrel at which point it attaches to the frame can be cut off of the old tube, and brazed onto the new one. Although this is done by some 'smiths, I believe it to be a very bad idea. I've had such a barrel break apart at the brazing.

"Tune-Ups":
This is the sort of thing that any really good pistol-smith does all of the time. Such work could, at your option, include lightening and shortening the trigger-pull, as well as controlling the trigger's over-travel, usually by means of a small, adjustable stop-screw.