Indicating Barrels to chamber

[Alex Wheeler]

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

Your 100% correct. We did go over it a bit on the 2nd page of this thread.

 

[urbanrifleman]

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"

That's pretty good huh?

Interesting idea checking runout on the reamer while it is sticking out.

 

[urbanrifleman]

Your 100% correct. We did go over it a bit on the 2nd page of this thread.

How do you tighten that up?

 

[Alex Wheeler]

Replace them with high quality ones.

 

[DaveTooley]

How do you tighten that up?

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[Edd]

There is a machine shop that will do an occasional job for me. They only make small parts. Some of them are really small.

I once asked the owner about tolerances. He said his machines could hold tolerances to a few tenths.

It surprises me that most of the machines used for Gunsmithing are more precise than his.

 

[HillbillyLongRifle]

Their not more precise. Very few gunsmiths have lathes that will hold that kind of tolerances!

 

[Alex Wheeler]

There is a machine shop that will do an occasional job for me. They only make small parts. Some of them are really small.

I once asked the owner about tolerances. He said his machines could hold tolerances to a few tenths.

It surprises me that most of the machines used for Gunsmithing are more precise than his.

Holding parts to a tolerance is different than how much runout a bearing has. If your bearings have no measurable runout, you can dial in a part very very well. Pushing in a reamer is a very low force operation and does not test the rigidity of the machine. And its a form tool which means it will cut the chamber to size so long as you dont influence it. Turning a batch of parts to a specific OD would be a very different question, and likely what he meant when you asked him. Tool wear, machine flex, tool changes, temps, and other things all come into play when running a batch of parts. Its a very different thing. For what we do, we dont need to repeat 1000 parts, we do one job at a time and we dont load our machines, its light work. I wouldnt own a lathe that had .0001" tir in the bearings.

 

[Dusty Stevens]

Since mine runs on an oil wedge i have to take into account my bearing temps and specific oil. Its hard to get one lined out when it only runs a minute at a time

 

[HillbillyLongRifle]

Dusty you have a Southbend Heavy 10?

 

[dnellans]

One other thing I noticed on my first 223 barrel (5r) is that it’s also noticable harder to get a small bore diameter dialed in than a 243 or 264. There just isn’t as much room on the grooves or lands and the radius of bore changes faster as well. I would say it took me 2x as longer than others I have done.

 

[Dusty Stevens]

Dusty you have a Southbend Heavy 10?

Yes and a 13

 

[Dusty Stevens]

One other thing I noticed on my first 223 barrel (5r) is that it’s also noticable harder to get a small bore diameter dialed in than a 243 or 264. There just isn’t as much room on the grooves or lands and the radius of bore changes faster as well. I would say it took me 2x as longer than others I have done.

You gotta get juuuust the right angle so that the other side of the bore doesnt hit the stylus back toward the indicator. Did a 17cal yesterday and it was tuff

 

[GenePoole]

Yes and a 13

But do you have one that is fire-plug red?

 

[HillbillyLongRifle]

Heres my 1963 Southbend 10L

 

[Dusty Stevens]

But do you have one that is fire-plug red?

No but it looks like a goodun

 

[Dusty Stevens]

View attachment 1234958Heres my 1963 Southbend 10L

Wish i had that one

 

[dnellans]

For those like me who haven't done a lot of barrels yet, I thought it might be helpful to share some videos of what my my chambers have been looking like. I've only done 6 barrels total now - 3 on the lathe of a real gunsmith who was willing to talk me through and now 3 on my own (a used grizzly 0750G with a DRO).

I've been documenting what my chambers are turning out like thanks to the $50 teslong and then will keep track of what they're shooting like to see if there is any obvious correlation. As mentioned earlier in the thread, I'm surprised what some look like that still shoot (maybe not benchrest standards) but pretty darn well.

I decided to clean and then chamber a used up barrel as my first test run on the new lathe after lots of adjusting and test cuts to be mostly happy with its form and function. The neat part about chambering a clapped out barrel is you can really see where you are taking metal from in the freebore and lands.

After doing that one (which I never shot) I was happy enough with the results that I did my first match barrel in 6 creed. It was a 5R and you can see what I think is a little deflection on this one due to 5R rifling. The edge of the lands all look good but in between them you can see that half-moon looking pattern.

Happy to report that 50 rounds in its producing .6 moa 10 shot groups at 900 yards from a harris bipod and rear squeeze bag. I don't have benchrest equipment so could be the gunsmith, the shooter, or the harris and squeeze bag at this point - I have no idea. But groups like that are more than good enough for my game.

Top right was an old barrel I chambered on the gunsmith's lathe, bottom was my first chamber on my lathe (shown above), left group was a buddy who apparently doesn't know what "left" target means, but thankfully can't call wind.



Hope those are interesting to someone - if any of you pro's take the time to wade through 5 mintues of chamber video, I'm always open to suggestions if you see something that looks funny or how to improve anything about it.

 

[urbanrifleman]

For those like me who haven't done a lot of barrels yet, I thought it might be helpful to share some videos of what my my chambers have been looking like. I've only done 6 barrels total now - 3 on the lathe of a real gunsmith who was willing to talk me through and now 3 on my own (a used grizzly 0750G with a DRO).

I've been documenting what my chambers are turning out like thanks to the $50 teslong and then will keep track of what they're shooting like to see if there is any obvious correlation. As mentioned earlier in the thread, I'm surprised what some look like that still shoot (maybe not benchrest standards) but pretty darn well.

I decided to clean and then chamber a used up barrel as my first test run on the new lathe after lots of adjusting and test cuts to be mostly happy with its form and function. The neat part about chambering a clapped out barrel is you can really see where you are taking metal from in the freebore and lands.

After doing that one (which I never shot) I was happy enough with the results that I did my first match barrel in 6 creed. It was a 5R and you can see what I think is a little deflection on this one due to 5R rifling. The edge of the lands all look good but in between them you can see that half-moon looking pattern.

Happy to report that 50 rounds in its producing .6 moa 10 shot groups at 900 yards from a harris bipod and rear squeeze bag. I don't have benchrest equipment so could be the gunsmith, the shooter, or the harris and squeeze bag at this point - I have no idea. But groups like that are more than good enough for my game.

Top right was an old barrel I chambered on the gunsmith's lathe, bottom was my first chamber on my lathe (shown above), left group was a buddy who apparently doesn't know what "left" target means, but thankfully can't call wind.

View attachment 1234974

Hope those are interesting to someone - if any of you pro's take the time to wade through 5 mintues of chamber video, I'm always open to suggestions if you see something that looks funny or how to improve anything about it.

I would find it very hard to believe the chambers shown in your video would be the limiting factor in your groups.

Those look pretty darn incredible to me.

 

[DaveTooley]

here's a couple of pics of the 223 chamber. Opposite sides of the throat.