Measuring Finished Chamber Dimensions

[Jud96]

What are you guys using to measure the back end of your finished chambers to verify they’re on size and not oversize?

I have a 0.2-1.2” inside mic I’m going to try and use, but I’m unsure how it’ll do on a tapered bore like a chamber.

I have heard of using pin gauges, but again since the chamber is a tapered hole I don’t know how well they would work.

Thanks

 

[Bob3700]

You could use a telescoping gauge n micrometer to measure the back of the chamber.

 

[DRK]

Chamber cast if you are not in a hurry.

 

[Will Henry]

I believe it was Jackie Schmidt who said (more or less), if you have the reamer, you have a pretty good gauge. Otherwise, your inside mic will work OK. Measuring to close tolerances is an art as much as a science. WH

 

[Jud96]

I believe it was Jackie Schmidt who said (more or less), if you have the reamer, you have a pretty good gauge. Otherwise, your inside mic will work OK. Measuring to close tolerances is an art as much as a science. WH

Thank you. I use mics everyday, so I’m comfortable with them, but measuring a tapered bored like a chamber is something I don’t have a lot of experience with.

 

[Tod Hendricks]

This works very good for the base and all the way to the shoulder and repeatable. https://www.penntoolco.com/electron...kyUKlYdxe1yvKD_g_CSxVawkJ8p5dyrAaAnmPEALw_wcB

 

[Kiwishooter]

This works very good for the base and all the way to the shoulder and repeatable. https://www.penntoolco.com/electron...kyUKlYdxe1yvKD_g_CSxVawkJ8p5dyrAaAnmPEALw_wcB

I've got a few of those from 6mm to 75mm they come in very handy for a lot of things.
Mine are all mechanical

 

[round]

Do you have a lathe ?

 

[liljoe]

A tapered mandrel. Maybe about 1 thou per inch.
You can slide it into the chamber and see how far it goes.
Joe

 

[Fuj]

I always do a chamber cast, bag and tag it, and into one of the Kennedy
drawers for future reference.

 

[Jud96]

Do you have a lathe ?

Yes obviously?

 

[DaveTooley]

Gage balls

 

[round]

Yes obviously?

You never said you chambered it yourself. You only asked how to measure it.

 

[Jud96]

You never said you chambered it yourself. You only asked how to measure it.

I apologize, I thought I said in my original post I was chambering the barrels myself.

 

[jackieschmidt]

If you are doing your own barrels, you really should critique your set up to insure that when you ream your chamber, it does come out the exact size of the reamer.
The reamer it’s self is your best gage. Take the live pilot off, slip the reamer into the finished chamber. It should have zero shake, or at least none you can detect that would be of any consequence.

Of course, any good machinist can use a simple snap gage, especially if you have a sample chamber that is correct to use as a comparison.

 

[Jud96]

If you are doing your own barrels, you really should critique your set up to insure that when you ream your chamber, it does come out the exact size of the reamer.
The reamer it’s self is your best gage. Take the live pilot off, slip the reamer into the finished chamber. It should have zero shake, or at least none you can detect that would be of any consequence.

Of course, any good machinist can use a simple snap gage, especially if you have a sample chamber that is correct to use as a comparison.

Thanks Jackie. My goal is to have a setup that makes good chambers, but I want to check every chamber to make sure they’re on size and correct. I have snap gauges, but prefer an inside mic.

I think I’ll just do some playing and see what I like best. I just thought I’d see what others are doing.

Thanks

 

[DaveTooley]

Thanks Jackie. My goal is to have a setup that makes good chambers, but I want to check every chamber to make sure they’re on size and correct. I have snap gauges, but prefer an inside mic.

I think I’ll just do some playing and see what I like best. I just thought I’d see what others are doing.

Thanks

I rely on the barrel setup ( most important ) and pushing the reamer to minimize any influence on the reamer. Myself and many customers have moved brass from one barrel to another with minimal sizing, which confirms my methods.

 

[Jud96]

I rely on the barrel setup ( most important ) and pushing the reamer to minimize any influence on the reamer. Myself and many customers have moved brass from one barrel to another with minimal sizing, which confirms my methods.

Yes I plan to also rely on a good setup. But the only way to prove the setup is good is to measure the results. So I just wanted to see how others were doing that.

Thanks

 

[Alex Wheeler]

You have to know your reamers actual size as well. Most likely its larger than the print.

 

[Tim Singleton]

My reamer is speced at 442 at the 200 line
I have a set of gauge pins in 1/2 thos the reamer cuts 442 as speced.
The gauge pins are a good way to confirm you do not have an oversized back end