Which pin gages for checking bore tightness?

Ok, question. Furman suggests using pin gages to slip through the bore to discover if any tightness or restrictions in the bore. What size pin gages would you suggest for 22LR, 44, 45 and 480?

A "minus" set that has all pins from .250 to .500. Then just add the ones necessary for the 22 LR.

And the half sizes are even more necessary for internal measurements. You can google for SAAMI specs and it will give you land (bore) and groove diameter you can more or less get a thou and a half on both sides of the bore measurement and should be in the range.

I have seen 45s all over the map. I currently have used .4415" through .443" and so far haven't needed anything outside those ranges for pilots for my reamers for 1911 and other 45 barrels for throating.

However, measuring a revolver barrel will be very close since it is the same SAAMI specs that describe these measurements but now you have the addition of "rows" inside the barrel behind the roll marked warnings on a lot of Ruger barrels, yes they impress this "lawyer warning" on the outside deep enough to raise ridges inside the barrel behind each line of text on the outside. A snug fitting pin gage will not go past these ridges on a heavily marked barrel, and if the pin gage is loose enough to go past them, the measurement is pretty much out the window anyway as far as accuracy goes.

I have not needed to do this but you could cut a pin gage off short enough to fit in the frame window to measure thread choke at the frame end of the barrel. I would hate to saw up that many pin gages because now you have to get down into the .4405" or below range and you need enough in half thousandths that will cover the effective diameter of the choke. Too expensive to be practical.

After one takes the measurements, what are these numbers used for? Well, the only one who benefits from them is the owner that simply must assign a number to an anomaly inside the barrel. This can be a very costly process and the number you arrive at is really not worth the cost. It really doesn't matter what the bore measurements are, since we use the groove measurements to assure we have a boolit of sufficient size to seal in the bore. Land to land measurements mean nothing if you want to get right down to it.

Here's what to do.. And this will effectively simulate what the boolit is subjected to when it is fired, you can feel it with your hands.. Take a plastic cleaning jag, patch it really tight into clean, dry barrel. Push this jag toward the frame and note how much effort it takes to keep the jag moving at a constant rate. Any change in the force required to do this, is a variation in the barrel. Old Model barrels will often go completely loos on the jag for about half an inch where the barrel meets the frame. The jag will lose ALL resistance because there is a slight bulge in the barrel, caused by torquing it into the frame.

Newer barrels with the lawyer warning, as you push and pull the jack back and forth in the rollmarked area you can feel these ridges much like driving a car over a rumble strip on the interstate. Don't laugh, some of them are really severe and will make you think of that BRRRRRRRRRT! noise that your tires make! Not kidding a bit!

When you get down to the barrel/frame juncture, if the jag doesn't change enough to notice, you have ZERO choke (YAY!!!!!) and you can figure the groove diameter on this barrel to be basically the same as it is at the muzzle, likely .451" on the nose for a 45 caliber Ruger SA revolver barrel. *IF* the jag gets moderately tighter, this is thread choke you are feeling, and it can be in the .001" to .002" range and the jag still pass through with moderately more effort than it took to keep it moving. Usually these can be successfully lapped out with a firelapping kit from Beartooth Bullets.

*IF* on the other hand the jag stops here in this area, and you have to nearly destroy a cleaning rod trying to BEAT it through the rest of the way, the choke is severe, .003" to .004" restricted, and this gun needs to go back to Ruger if you can sweet talk them into rebarreling it. Barrels this severely choked do not respond well to firelapping as so much is required to lap this severe choke out, that you can damage the rifling in the good part of the barrel enough to pretty much ruin the barrel. If the gun is stainless, it is almost a sure bet that by the time you lap a severe choke out of it, the barrel is ruined. Either have the gun rebarreled or sent out for Taylor Throating which will cure it without ruining the rest of the barrel.

In closing, you can do all you need to do inside the barrel with the cleaning jag, I wouldn't even bother with pin gages for this purpose.

Let me also add this to the longer than normal reply above.. Regarding thread choke and lawyer ridges, you can remove the cylinder, place a piece of white paper on the recoil shield and shine a bright light on the paper. You can now look down the bore and see with your naked eyes any anomalies in the size of the bore. Those ridges stick out like a sore thumb! Thread choke looks like a hazy distorted circle about half in inside the end of the barrel. If you do this, and you can't pick out ANY deviation in the reflection of the light at the frame junction, you likely won't feel any with the cleaning jag either. It really is easy to detect.

New Model Flattops and Medium Frame Vaqueros.. Guns with the 3 digit prefix in their serial numbers. The examples of these that I have had in my shop have been by far the BEST fit and finish Ruger revolvers that they have EVER made. The barrels in these 44 and 45 caliber guns have been near flawless in my opinion. I have yet to see one with much of a thread choke. They seem to have gotten it down when they made these, and they are the darlings of the ball if you ask me. I was SO favorably impressed with guns I did for customers, that I had to go buy me one for myself. I picked one from Armslist that had 50 rounds of lead fired through it, the gun arrived and it is PERFECT. They moved the rollmarked warning to the bottom, made it very lightly impressed into the barrel, and there is absolutely ZERO variation in groove diameter where it meets the frame. For me, this certainly was a first and a welcome one at that! Ymmv!

Doug,

Thank you for your reply. Guess I could save myself about $50 + shipping on 14-18 new pin gages when I could simply "look" and/or feel as well as measure lead slugs, pushed through.

Alan