I don't even know the proper name for them. Plug gauges? Pin gauges? I apologize for my gap in knowledge but could you help a growing revolver shooter a hand?

https://www.mcmaster.com/pin-gauges/
Here you go.

Round balls or soft cast bullets work too if slightly oversized if you dont want an entire set of gauges.

Just go to eBay and type in pin or plug gauge. There will be lots of options. Most common set for this kind of work is the .250-.500 set. I didn't know how much I'd use a set but got a great deal on a used set with free shipping and no Alaska exclusion. I'm sure he regretted that. I've used them a lot on my own revolvers and those of friends. There seems to be new additions to the revolver ranks pretty frequently so mine do see a fair bit of use.

eBay would be my first stop as well. It's where mine came from after a Mike Venturino article mentioned them. They are used a surprising amount around my house.

Bronwnell's but Ebay might be cheaper.

Also, pin gauges come in plus (+) and minus (-) sizes, be sure to get the minus (-) or they won't fit in the throats.

Tracy,

Unless you want to own a set, I have a full set. I recently sent a handful off to a fellow member and he returned them with a $10 bill to cover shipping on my end. I would be more than happy to offer the same to you. Advise the sizes you want and I'll get them in the mail. Note I heading to Idaho for the summer on Friday.

Actually, they come with a plus or minus tolerance. Most commercial pin gage sets come with either a +0002 or a -.0002 tolerance. That said, having used, and checked hundreds of them over the years, I don't think I've ever found a commercial pin gage that was anywhere near .0001 off either side of the nominal. You can only come within a thou of determining throat size with them anyway. All you know for sure is this one goes in, but the next bigger one doesn't.

Handier than plug gages are taper gages, you just put them in the hole and take a direct reading. They're somewhat spendy, though, for a hobbyist with a limited number of hole sizes to ever have to check.

If you really want to go all out, another option is internal micrometers, but the cost there is a little the other side of nuts.