I’ve read here that bullets should be .001” bigger than the bore for best accuracy.

1. Is this the right measurement?

2. What is the proper way to measure the forcing cone, just use calipers at the very front of the opening?

3. Are the cylinder throats measured with calipers as well?

4. Do I need to take some new LSWCs and tap them through the cylinder holes using a dowel and small hammer, then measure and use the largest one, smallest one or whi

NOTE: The above post will not let me edit it.

“Areas,” not Aresh one in the Subject Line. Autocorrect error.

“Which,” not whi... at the end.

5. Is a LSWC used to measure the forcing cone from the cylinder side, tapping it partially into the forcing cone taper - say 1/2 way - then using a very small object like a dowel tapped from the barrel to gently drive it back out, then measure with calipers?

Sorry for such a weird looking thread!

Forcing cone plug gauges are here:

BROWNELLS BARREL CHAMFERING PLUG GAUGES | Brownells

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Ret. LE, FA Instr, S&W Armorer

The chambers throats of S&W revolvers are very slightly choke bored. If you want an accurate measurement, you need pin gauges. You could slug the throats, best done with a pure lead slug. If you do this, make sure you remove the cylinder from the firearm and properly support it while slugging.

As Armorer951 states, the best way to measure the forcing cone is with a plug gauge. They're about $60. You can get a rough idea with caliphers.

I'd suggest you simply shoot the cotton picking gun before you start worrying about theoretical aspects that can affect ultimate accuracy. The greatest factor affecting accuracy in any firearm is who's pulling the trigger.

^ Makes sense. From reading things on here practically every day, I was under the assumption that it was pretty common.

I like the “just shoot the thing” advice!”

I agree...shoot that puppy.

The only measuring tool I employ, when looking at potential revolver purchases, is Brownells range rod. I can eyeball the cylinder gap and there are things I can fix myself. However if the range rod does not drop through, it means there is a problem that I don't have the ability to fix or wish to deal with.

If you don't want to spring for a FC gage set (I haven't), I use a fired case from that gun to get an idea if the FC is too small or too large.

The max. spec is .020" over bore size so a .357 Mag shouldn't have a FC over .3770", IIRC. A case is easily mic'd. My pin gages are too long to fit in the cylinder window & I don't find using a caliper in it fits any easier.

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Waiting for the break of day

I made a tapered brass piece. Slide it in a new 357 barrel and marked it, slide it in a nice new 44 barrel and marked it, slide it in a new 45 barrel and marked it. I mostly do 45 conversions, but that is what I use for a gauge. I have used several 45 acp barrels to make 45 colts. As I like the longer cylinders for 45 colts the barrel shank needs shortened and I have a cutter for that. I figured the tapered tool thing out when thinking about how to guage the depth of forcing cone cut, using the barrel in orginal configuration to make my gauge.