Indicating Barrels to chamber

[Alex Wheeler]

You can do it that way. I am just throwing out all the methods commonly in use. I have never really posted what I do because I dont have a set way of doing it. I make decisions based on what I see once I have an indicator in the barrel. If you choose to run the reamer in the whole way then you would want the back end dialed in. The one thing everyone can agree on is that the throat needs to be concentric to the bore. Or maybe the grooves? Ok, we cant all agree, lol.

 

[Dusty Stevens]

Don't you dial the breech (say an inch in) and a point beyond the throat (or as far as you can reach with the indicator)?

I never understood dialing the muzzle to zero on the other end of the barrel... the barrel is crooked to some extent, that is a given, the only thing of interest would be the part where the chamber sits, right?

Forgive me. I am just trying to ask good questions... maybe I am failing. I admit some of the things I have heard about dialing in barrels makes exactly zero sense to me.

Good barrels arent as crooked as the internet leads you to believe. Take that new indicator and dial in right in the throat and at the back end making them both the same if you dont want to drill or bore. Once you do that check the muzzle and see what it does. This is where youll see the most difference in a good barrel or budget barrel. Have you read the 130page chambering pdf that butch lambert so kindly compiled in the advanced gunsmithing forum? Take those 100 methods and figure out what parts of each you like and put them together in your own method. Everybody has their own way according to their available equipment and knowledge/experience. You may find that with your setup that chambering between centers will yield acceptable accuracy for your needs

 

[urbanrifleman]

Good barrels arent as crooked as the internet leads you to believe. Take that new indicator and dial in right in the throat and at the back end making them both the same if you dont want to drill or bore. Once you do that check the muzzle and see what it does. This is where youll see the most difference in a good barrel or budget barrel. Have you read the 130page chambering pdf that butch lambert so kindly compiled in the advanced gunsmithing forum? Take those 100 methods and figure out what parts of each you like and put them together in your own method. Everybody has their own way according to their available equipment and knowledge/experience. You may find that with your setup that chambering between centers will yield acceptable accuracy for your needs

Chambering between centers with the barrel floating in the steady makes the most sense to me if I was doing a blank from scratch. The reamer follows the hole if you let it would be my thinking.

Problem is that doing other jobs that way are not always practical.

I have been studying methods for a while now. Did not know what equipment to get, but methods I have been looking at all of them for about six months.

I am not a machinist, but I am an engineer and have many years in gauge and process control (including Six Sigma which I have two belts). Many of the methods make no sense, and would never hold the tolerance people claim if repeated many times. Stacking tolerance on tolerance.

Truthfully (and I am just being honest) I am not sure about a lot of things making a difference. Some barrels shoot, some don't. It is almost like you have to try to make the chamber crooked by forcing things, or the machine itself is a sloppy, loose POS (which could certainly be the case).

Take everything I am saying with a grain of salt, I am just observing and noting at this point.

Indians and not arrows... is my observation.

 

[Dusty Stevens]

Chambering between centers with the barrel floating in the steady makes the most sense to me if I was doing a blank from scratch. The reamer follows the hole if you let it would be my thinking.

Problem is that doing other jobs that way are not always practical.

I have been studying methods for a while now. Did not know what equipment to get, but methods I have been looking at all of them for about six months.

I am not a machinist, but I am an engineer and have many years in gauge and process control (including Six Sigma which I have two belts). Many of the methods make no sense, and would never hold the tolerance people claim if repeated many times. Stacking tolerance on tolerance.

Truthfully (and I am just being honest) I am not sure about a lot of things making a difference. Some barrels shoot, some don't. It is almost like you have to try to make the chamber crooked by forcing things, or the machine itself is a sloppy, loose POS (which could certainly be the case).

Take everything I am saying with a grain of salt, I am just observing and noting at this point.

Indians and not arrows... is my observation.

Im a black belt. Too much time with jack welch

 

[Alex Wheeler]

Good barrels are certainly better than mid range ones. Im to the point I will only chamber the best ones. Its not worth fighting. Even still a good Krieger or Bartlien will still run out at least a few tenths at the back end if you dial other areas. I don't know if Im considered the internet or not but I chamber about 150 barrels a year, mostly for Benchrest. I pay very close attention to what I see.

 

[Dusty Stevens]

Once you get going youll figure out what matters. What matters to some may not make a difference to others. Some need a full br style chamber and some dont but its up to you to decide what youll provide your customers and what they care about or can notice

 

[Dusty Stevens]

Good barrels are certainly better than mid range ones. Im to the point I will only chamber the best ones. Its not worth fighting. Even still a good Krieger or Bartlien will still run out at least a few tenths at the back end if you dial other areas. I don't know if Im considered the internet or not but I chamber about 150 barrels a year, mostly for Benchrest. I pay very close attention to what I see.

By some of these posts on here youd think a barrel bore is at least 6” out

 

[Alex Wheeler]

Well, that would be a little crazy. But if a freebore diamter is .2435 in a 6mm, and the groove is .2430", you only have to be off .0003" to have a freebore on one side, and rifling back to the neck on the other. And many makers allow .0003-.0005 over nominal on the groove. So you may get a .2435" barrel. Now a .0001 matters to the bore scope. So a couple tenths really matter here, in my opinion. A chamber thats .001" off would be terrible.

 

[Alex Wheeler]

This barrel fought me a little. I could tell there was a high spot in the middle because I chased it a bit. When a groove is not uniform you need to dial EXACTLY in the same spot in each groove (assuming all the groves are the same, and many are not) Or land if thats what your dialing. The first picture shows the area since I was dialing in the center of the groove. The peak is the high spot that fought me because its hard to index at the peak every groove. (also note the lapping scratch through the freebore) it was un measurable. The difference between the high and low spot was .00005". Half a ten thou, and yes I could see it with the long interpaid. The second picture is a little ratchet on one side of the groove. It measured .0001" higher than the center. I post this for two reasons. Irregularities you see in groove shape are usually tiny, tenths usually. But they are there and some seem to produce barrels with minimal issues. If you want to dial to the tenth, the barrel must be made to the tenth. Ratchet and other irregularities reduce your ability to produce the best chamber.

 

[urbanrifleman]

Very awesome thread. VERY AWESOME!!!

BTW, my carbide insert lathe tools arrived today. Yay!

 

[Danny1788]

Very awesome thread. VERY AWESOME!!!

BTW, my carbide insert lathe tools arrived today. Yay!

Not all carbide is made the same FYI. I have tried several different types to settle on my one all be all for my lathe. And that might all change if I go to a 3ph motor.

But I will say their are a lot of very good gunsmiths commenting on this post and you should listen to what they are trying to teach you. They are giving free knowledge. I was in the same boat about 5yrs ago, I don’t do it for a living just a hobby but these fine gentleman are a big help. Also you won’t really understand what they are trying to say until you have chamber more than a few barrels. It’s trial and learning.
My hats off to them, I have learned a lot from these guys and continue to learn. So a thank you to the gunsmiths that have replied and that have helped me

 

[rhovee]

Just get a 1.250 straight 34” blank and have at it

 

[hoz53]

Just get a 1.250 straight 34” blank and have at it

now thats some good advice. Thats what i did. Cut it off and redo for alot of practice. I just wished i would have bought the best blank i could have got instead of the one(s) i did.

 

[hoz53]

Not all carbide is made the same FYI. I have tried several different types to settle on my one all be all for my lathe. And that might all change if I go to a 3ph motor.

But I will say their are a lot of very good gunsmiths commenting on this post and you should listen to what they are trying to teach you. They are giving free knowledge. I was in the same boat about 5yrs ago, I don’t do it for a living just a hobby but these fine gentleman are a big help. Also you won’t really understand what they are trying to say until you have chamber more than a few barrels. It’s trial and learning.
My hats off to them, I have learned a lot from these guys and continue to learn. So a thank you to the gunsmiths that have replied and that have helped me

Me To and ill say the same-- Thank You to you guys that helped me

 

[hoz53]

This barrel fought me a little. I could tell there was a high spot in the middle because I chased it a bit. When a groove is not uniform you need to dial EXACTLY in the same spot in each groove (assuming all the groves are the same, and many are not) Or land if thats what your dialing. The first picture shows the area since I was dialing in the center of the groove. The peak is the high spot that fought me because its hard to index at the peak every groove. (also note the lapping scratch through the freebore) it was un measurable. The difference between the high and low spot was .00005". Half a ten thou, and yes I could see it with the long interpaid. The second picture is a little ratchet on one side of the groove. It measured .0001" higher than the center. I post this for two reasons. Irregularities you see in groove shape are usually tiny, tenths usually. But they are there and some seem to produce barrels with minimal issues. If you want to dial to the tenth, the barrel must be made to the tenth. Ratchet and other irregularities reduce your ability to produce the best chamber.View attachment 1234603View attachment 1234604

Some of the stuff you see in these bores continues to amaze me. You are one skilled guy. And I need to make a chuck like that one you have for myself.

 

[urbanrifleman]

Not all carbide is made the same FYI. I have tried several different types to settle on my one all be all for my lathe. And that might all change if I go to a 3ph motor.

But I will say their are a lot of very good gunsmiths commenting on this post and you should listen to what they are trying to teach you. They are giving free knowledge. I was in the same boat about 5yrs ago, I don’t do it for a living just a hobby but these fine gentleman are a big help. Also you won’t really understand what they are trying to say until you have chamber more than a few barrels. It’s trial and learning.
My hats off to them, I have learned a lot from these guys and continue to learn. So a thank you to the gunsmiths that have replied and that have helped me

Oh, I am listening. I have listened for hours of chambering discussion sitting around the table at the restaurant listening to David Tubb and his friends. There is certainly more than one way to skin a cat.

I bought mine from Shars tools. My lathe is 3 phase also.

 

[JMA]

This barrel fought me a little. I could tell there was a high spot in the middle because I chased it a bit. When a groove is not uniform you need to dial EXACTLY in the same spot in each groove (assuming all the groves are the same, and many are not) Or land if thats what your dialing. The first picture shows the area since I was dialing in the center of the groove. The peak is the high spot that fought me because its hard to index at the peak every groove. (also note the lapping scratch through the freebore) it was un measurable. The difference between the high and low spot was .00005". Half a ten thou, and yes I could see it with the long interpaid. The second picture is a little ratchet on one side of the groove. It measured .0001" higher than the center. I post this for two reasons. Irregularities you see in groove shape are usually tiny, tenths usually. But they are there and some seem to produce barrels with minimal issues. If you want to dial to the tenth, the barrel must be made to the tenth. Ratchet and other irregularities reduce your ability to produce the best chamber.View attachment 1234603View attachment 1234604

Another big consideration if you want to indicate to a tenth is your lathe spindle must be capable of it.
Many are not.

 

[Dusty Stevens]

Thats a very good point ^^^

 

[DaveTooley]

FWIW
I just chambered a 223rem for a BAT action. I don't have a core drill for 5.56 so I drilled and did a two stepped bore to true the hole. Maybe .350" deep as I just free handed the feed. Just finished the chamber. I use a pusher which lets the reamer find its own path. I cut the last pass and for the hell of it I measured the runout on the reamer shank. This is 4.400" away from a snug fitting bushing. It ran .0002" TIR. I never cleaned the chamber out, just let the coolant flush it out. The runout could be caused from left over crud from cutting the chamber.
Edit; I dialed the throat in and checked the runout just inside the breech. It went from a few tenths in the throat to .0017"TIR about .500" in. Total distance between point maybe 2"

 

[Alex Wheeler]

One of the best barrel manufacturers told me that a half point of rockwell change was enough to make the drill walk off center and that slight variations in hardness are one of main reasons a bore wanders slightly. I would say thats no different when it comes to reaming a chamber.