Bearcat,

To find out what you need to know you don't have to actually measure it. There are two things to check, an un-fired bullet in the cylinder throats is first. A bullet should pass through the throat with little or no resistance, but not too loose. Second, slug your barrel and try the slug in the throats. You will need a quite soft bullet to do this as it needs to be able to expand to fit the barrel. Once you have a slug try it in the throats. This should also pass through the throats but can have slightly more resistance which indicates the groove diameter and throat diameters are close. If the slug won't fit the throats then they are tighter than the barrel and need to be opened up.

There are several reasons people have with commercial cast bullets. Most are sized to nominal diameters, .44 bullets typically .429. This is actually too small for many revolvers and there is gas blowby. Another problem is most of the lubes on commercial bullets are more intended to be pretty and stay on the bullets during handling instead of being chosen for their lubricating qualities. Finally, most commercial cast bullets are entirely too hard for revolvers. Many are 20 Brinell or harder. Except for the very highest pressure loads a hardness of 12-15 Brinell is better than harder.

Here are three things to do. First, after determining if the bore or throats are larger and the throats enlarged if needed, slug the throats and measure the slug. Order bullets from a company which lets you select the sizing diameter and order bullets no more than .001 smaller than your throats. Second, if they don't use a soft lubricant, but a bottle of Lee Liquid Alox and tumble lube the bullets before loading. Third, settle for loads in the 25-30,000 PSI range and velocities not more than 1250 FPS. Chances are you will be a lot happier with cast bullets.