But the gauges are like pieces of rod that have been precision ground on their OD to exact tolerance from 1/4 inch to 1/2 inch in one thousands of an inch increments. There are a bunch of them in that box and I hope to God that I never drop the box and spill them out of their specific hole. That will be a half days job getting them all back in order!
So you can use them to check the size of a hole to within one thousands by sticking them in the hole, going up in size till the next one wont fit. Simple to use but very precise. And you can get them in plus and minus sizes but one thou spread is close enough for most things on a gun.
I got out in the shop last Sunday and played with them a bit and found out that you can measure all sorts of things with them. I ran them down the bore on my rossis and learned something..... I think when they cut the rear dovetail in the rossis, I think that the mash it in instead of cutting!
On my 45colt, a .445 will start in the muzzle end of the barrel and will go about 4 or 5 inches and stop cold. Hummm...... But a .444 will go in past this spot, but then stops right at the dovetail cut. Hummmm.....443 no so maybe a .442 no, how about a .441??? YES it finally made it past the dovetail and out the chamber end, but was a little stiff getting past the dovetail.
That's 4 thousands smaller than the muzzle end of the barrel! This is why when you slug a barrel, you sometimes get that one set of lands that measures a little smaller than the other two. That's actually the "grooves" that you are measuring, but if the lands are mashed down, the grooves are too, right under the dovetail. I have read about this but thought what the heck, They ough to know how NOT to do that and the one I'm reading about is probably just a fluke and does not happen to but a very few.
Well I got three of those "very few" cause my 454 and 357 all have it. They were only .002" smaller and not .004, but that shows you that is is more of a common thing, than not. And I'm not picking on just rossi, this is just the first gun that I have looked for it on. The odd one was my 44 mag it had one size from chamber to muzzle all the was, and the bore was snug on the gage all the way too. BUT WAIT A MINUTE!! The 44 was the first rossi that I bought and for some reason I remember fire lapping the barrel. I had just read a big write up on fire lapping and wanted to give it a try. I did it but don't know if I helped anything or not, cause it has always shot good. But then so does the 45 colt.
I then checked the throats on my 45c blackhawk. It measured out just like I had measured it before by slugging each throat in the cylinder, .455, .455, .4545, .454, .455, .455. So I size at .4535. Someday I may try to get them all a little closer to the same. But that was the good thing, the bad thing showed up when I slid a gage down the barrel. I forget the exact size now but it went in good and I could feel a little resistance all the way until I got right to the front edge of the forcing cone where the rifiling starts. Then it stuck, I thought that I could push it through, but it would not go even when I taped the cleaning rod that I was using as a push rod.
So now I know that I have the other bad thing that happens to a ruger. When they screw the barrel in, they torque it down really tight, and it collapses the end of the barrel that sticks in at the cylinder. The 45s are the worst about this cause the barrel is the thinnest because of the big bore.
So I made up some lapping bullets and headed for the range. I shot 40 course and 10 fine through both guns. When I got home I stuck the .441 gage in the rossi and turned the muzzle up, and the gage fell all the way through
feeling lucky, I tried the .443, it hit the floor too. Hell, this is making me think that I actually know what I'm doing!!!......The .444 is stuck in the barrel right now. It was late and it will just have to wait till tomorrow.But that was a big improvement, and Ill make up some more lapping bullets and give it another try soon. I want it to be like the 44 and get it to where the .445 gage will go all the way through, with a slight drag on it the entire length.
The blackhawk still did not free up all the way. I can tell that some of the restriction was removed cause the gage is a little deeper into the forcing cone. But it too is going to take some more lapping, or maybe recutting the forcing cone at 11 degrees so that it goes into the bore further and gets past the restriction. And to think, I bought that ruger around 1975, and have been real happy with it's accuracy this whole time. If it improves a little after I get the restriction out of it, it will be just wonderful.
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