Measuring the cylinder throat of a revolver

[IrvJr]

Hi Folks,

I have a Ruger Superblackhawk in .44 mag/.44sp that doesn't shoot as well as I'd like it to. I've tested it at 10 and 25 yards, and it only provides marginal accuracy, especially when compared to my other single action revolvers (Ruger Blackhawk .45 and Ruger Single Six). Someone mentioned that I shoud check the cylinder throats of the gun to see if the holes are too tight.

What's the best way to do this? I've read somewhere that there are some spring loaded gages that can be used to measure the inner diameter of the throat - has anyone heard of these gauges? If so, where can I find an online source of these gauges (I already checked Brownells).

Or is it sufficient to drop a brand new bullet through each chamber and see if it slides through the throat without resistance?

Thanks!

 

[BBBBill]

Small hole guages. You put them in the hole, turn the expander knob till it fits the hole, then remove and measure with a mic. You can find them at most industrial equipment supply houses.

 

[Backwoods]

If you're going to try this, use a jacketed bullet. I seem to recall most of mine coming in boxes that list the nominal diameter.

If the slug doesn't drop thru, you can reasonable assume that the throat is too tight. If you need to be more precise(recommended) find someone with an adjustable hole gauge and a micrometer. A dial caliper will work but is only moderatly precise if not used properly.

Don in Ohio

 

[Tom C.]

I have a set of pin gages that I use for measuring cylinder throats. The throats of my SS 5.5" Super Blackhawk is .431" which is great and it shoots great. My .45s were all a little small and benefited from getting the throats reamed.

 

[Bad Flynch]

The old-fashioned way to do this is to use dead soft lead, or lead slugs.

1) clean all cylinder throats and lightly oil them.

2) drive a moderately oversized dead soft lead slug through each hole. Yes, they vary, even in a single revolver. Make certain that they are slightly oversize so that the soft lead slug is swaged by the hole. The cylinder should be well supported for this maneuver.

3) measure the lead slugs, carefully, with a micrometer.

While you are in the business, measure your barrel's groove diameter, too.

Have fun.

 

[HSMITH]

Take a soft cast lead bullet, set it down nose first on a hard surface and smack it lightly with a hammer to expand it. Expand it until it will just start into the chamber. With the cylinder OUT of the gun and supported well tap the slug through a LIGHTLY oiled chamber with a soft brass punch. Scratch the chamber number on the base and set it aside (number chambers from some identifying mark on the cylinder and count clockwise from there). Do this for all 5 or 6 holes. Measure them carefully and compare them to the other chambers. Now you have an idea of what you are working with.