I realize the purpose of the "forcing cone" in a revolver barrel is to funnel a bullet down the barrel after it has jumped from the cylinder. But as I understand it, if the forcing cone is too large (however big is too large) then the pistol's accuracy goes to hell.

My question is, if you get a pistol with an oversize forcing cone, what can you do about it? Shoot oversized bullets? What does a guy do about this issue?

How do you measure the forcing cone?
How big is too big?

Pecos 45

Look on page 128 in the Brownells catalogue #56. They have "barrel chamfering plug guages" to determine the minimum and maximum throat diameter.

If someone has opened the throat up too far you can set the barrel back one turn and re-chamfer.

Thanks, Craft. Will do.