? chucking up a barrel ?

Another Method . .

This seems to work and really averages out the bow, runnout, and the nucences in the barrels: Please note: I have a Proto-TraK CNC Lathe that has a long spindle bearing area - I cannot indicate the muzzle end of a 34" barrel by sticking it through the lathe. This has some fine advantages too! You can also turn one of these devices that will attach to the rear of your lather for perfect chamber jobs everytime.

1. Insert barrel into the chuck at crown end and use the barrel manufacturers center on the chamber end into a live center.
2. Now cut a .100 45 degree chamfer on the full length blank (you will be cutting this off later). It is not critical to have this within a 0.0001"....it is a reference point for the original gun-drilling operation when the barrel-maker made the blank.
3. Now remove blank and flip it around for muzzle work. The barrel is inserted into the spindle where it is supported with a spring loaded-moving center that is located within the ground and nearly perfectly zeroed spindle bearing region (or you can make a device that attaches to the back of your lathe to do the same thing).
4. Now the barrel is lightly pushed and pre-loaded axially (in line with the bore) by this "Centering Spindle Device". The chamber ends' 45 taper rides up another reverse cone within the spindle using the centering spindle device. Additional load is supplied 15-45 lbs axially. Now the uncut chamber end of the barrel blank is running within 0.001" TIR within the spindle.
5. Cut muzzle end and pre-cut a straight crown
6. Indicate both bore and lands to within .0002" if possible - Else choose the bore since bullet is extruded to this.
7. Now cut your favorite crown.
8. Now cut a .050" 45 degree chamfer or a 0.075" Radius on the barrel end. Muzzle end finished!
9. Now remove barrel and insert the crown end into lathe - you have already measured length to cut off. Use copper wire method so not to influence or bend barrel once tightened. Again, Centering spindle device "picks-up" the 45 chamfer (or radius) on the finished crowned muzzle end) within the spindle. Spring-loaded device centers muzzle to centering device within tenths. Allow barrel to protrude just enough for tenon.
10. Tighten 6-Jaw bump chuck (not over-tight). Apply pre-load spring center up device and barrel. Tap end of barrel lightly with dead blow mallet to allow taper and spring pre-load to perfectly center barrel.
11. Cut off barrel and cut clean and bur free. I use my crowning tool (CERMET - high positive) and cut at 2000 RPM. For a mirror finish and no bur!
12. Indicate bore and grooves within a 0.001.
13. Insert Gritter rod with proper bushing (weighted to load - I agree) and indicate bore. I measure the reamer and determine where the bushing area will be positioned within the chamber - this is the critical dead "ZERO" location that needs to be verified and indicated to "ZERO" when done. High pressure coolant is turned on which fills the barrel and the Gritter rod is walked in while spindle is running at 100 RPM. Use Bump chuck to center barrel. You will see everything with in barrel! Continue to use bump chuck- look at end of barrel, look at runnout of bushing finish area and walk rod into bore 6-8" past finished throat area. SO........we now have the bushing area "DEAD ZERO" , the end does not matter (we will drill/bore) and the bump chuck was used to make sure everything ahead of freebore is zeroed. In summary, Muzzle is perfectly centered to spindle (spring loaded spindle thingy), throat area and 2-6" towards muzzle are zeroed.
14. Choose action type - Press go and machine entire Tenon (drills for chamber needed, pre-bores (straight -no taper) chamber, thread.
15. Insert reamer - High pressure coolant on and finish last 0.10" using reamer.
16. Check headspace.

First barrel takes 1 hour-15 minutes.....second, third etc take 30 minutes each

Side note high pressure coolant allows going almost to finish depth without cleaning. High speed steel reamers are run at 350 RPM and carbide at 1050 RPM! Reamed chambers must roughed up in bottle area due to extremely polished finish.

I will post some pics if interested.
 
Runout question

I am fairly new to doing chambers in the headstock and this is what I have ran into in dialing in a Bartlien Barrel. I have indicated the muzzle with a range rod to .0001 and I indicated 1 1/2 in on the chamber end with a DTI to .0001. When I back my DTI to where the chamber will start I get .0006 runout. When I dial in both spots in the chamber end (where the chamber will start and 1 1/2 in. in) I get .025 runout at the muzzle. I know I can only use two points to go off of but not sure which two will be best......
Thanks,
Jonathan K
 
Some of what you are reading at the breech end of the barrel isn't usable as to dialing in the barrel because of lapping the bore and the belling out of the end of barrel from lapping the barrel. The chamber takes care of the belling on the breech end. That's why I consider the initial dialing in with a pin as a rough dial in, then finish up by getting the projected throat dialed in where I want it.

Still haven't received my Grizzly rods from Pacific yet. I still think with the majority of barrels you can chamber them any way you want within reason and get a good chamber and a good shooting barrel. Then you'll have a few problem barrels that will be hard to get good chambers in no matter how you do it. We'll see when the rods come in, if they change my methods or not. When you quit trying new ideas, is when you quit improving.


Was looking in an old benchrest book from the '50's, the world record 5 shot group at 200 was about a .450" or so. There were quite a few groups that were signed by lots of people all over the target, that nowadays would be thrown away at the end of the match as just another group. What it's going to take to improve to the next level from where we are now, I don't know. But, if you don't keep trying to improve, you'll never get there.
 
JohnathanK,
My vote says go with the chamber in line and ignore the muzzle end.

Look at it this way, if you go back to aligning the chamber with the muzzle, you have the chamber area out .0005 in 1 1/2" and thats a bunch.

Some will say that the reamer will follow the bore, but, in your case it would have to wobble, and that ain't likely.
 
JonathanK said:
I am fairly new to doing chambers in the headstock and this is what I have ran into in dialing in a Bartlien Barrel. I have indicated the muzzle with a range rod to .0001 and I indicated 1 1/2 in on the chamber end with a DTI to .0001. When I back my DTI to where the chamber will start I get .0006 runout. When I dial in both spots in the chamber end (where the chamber will start and 1 1/2 in. in) I get .025 runout at the muzzle. I know I can only use two points to go off of but not sure which two will be best......
Thanks,
Jonathan K
Click to expand...
Johanathan, take Mike Bryants advise, drill out that back part, then prebore. That will get rid of your runout and give the reamer a good place to start.. Go to his web site and read how he chambers and do it that way.

http://www.bryantcustom.com/articles/rebarrel.htm

Mike, one of your customers, James Remmel, shooting his 6BRDX/BAT/Bartlin you built really did some great 600 yard shooting Saturday at Piedmont, NC.
 
Last edited:
Johanathan, take Mike Bryants advise, drill out that back part, then prebore. That will get rid of your runout and give the reamer a good place to start
Click to expand...

So you've removed the axial runout in the chamber area, So what are you going to do about the runout in front of the chamber, just ignore it? That just makes the whole point of dialing in the chamber area a waste of time. Keep in mind that .ooo5, is .001, which becomes .0017 in 3 dimensions.

Why buy and use .0001 measuring devices just to bore out what gets in your way. Machinists do not operate that way.
 
TRA,
As I said, you need to qualify some of your statements. You must not have any real machinest training. If you think you are doing it Gordy's way, you need to read his method again. He tries to do the best he can to get 2 places indicated as best possible.
If a person indicated the leade or throat and taper bored to that point, how far off would the end of the bullet be in your estimation? Well, I will tell you. At .0005 in 1.5" the tip of the bullet would be approx. .00017 off axis. If you say that makes a difference and you do that your name must be on all the equip. lists.
Most of this chambering method BS is just that. It just gives us a chance to sling it around.
Butch
 
Sounds as if someones goats are loose again.

Oh ya, what would you prefer, butch, pictures of medals, trophies, or my bank account? There's about a 10,000 competitive shooters around the world for every one b lambert, so I don't consider your narrow mindedness as relevant to much of anything, there's guys like you in every venue. If you are really quiet you can sometimes hear them hacking away.
 
Last edited:
PR2Shooter said:
This seems to work and really averages out the bow, runnout, and the nucences in the barrels: Please note: I have a Proto-TraK CNC Lathe that has a long spindle bearing area - I cannot indicate the muzzle end of a 34" barrel by sticking it through the lathe. This has some fine advantages too! You can also turn one of these devices that will attach to the rear of your lather for perfect chamber jobs everytime.

1. Insert barrel into the chuck at crown end and use the barrel manufacturers center on the chamber end into a live center.
2. Now cut a .100 45 degree chamfer on the full length blank (you will be cutting this off later). It is not critical to have this within a 0.0001"....it is a reference point for the original gun-drilling operation when the barrel-maker made the blank.
3. Now remove blank and flip it around for muzzle work. The barrel is inserted into the spindle where it is supported with a spring loaded-moving center that is located within the ground and nearly perfectly zeroed spindle bearing region (or you can make a device that attaches to the back of your lathe to do the same thing).
4. Now the barrel is lightly pushed and pre-loaded axially (in line with the bore) by this "Centering Spindle Device". The chamber ends' 45 taper rides up another reverse cone within the spindle using the centering spindle device. Additional load is supplied 15-45 lbs axially. Now the uncut chamber end of the barrel blank is running within 0.001" TIR within the spindle.
5. Cut muzzle end and pre-cut a straight crown
6. Indicate both bore and lands to within .0002" if possible - Else choose the bore since bullet is extruded to this.
7. Now cut your favorite crown.
8. Now cut a .050" 45 degree chamfer or a 0.075" Radius on the barrel end. Muzzle end finished!
9. Now remove barrel and insert the crown end into lathe - you have already measured length to cut off. Use copper wire method so not to influence or bend barrel once tightened. Again, Centering spindle device "picks-up" the 45 chamfer (or radius) on the finished crowned muzzle end) within the spindle. Spring-loaded device centers muzzle to centering device within tenths. Allow barrel to protrude just enough for tenon.
10. Tighten 6-Jaw bump chuck (not over-tight). Apply pre-load spring center up device and barrel. Tap end of barrel lightly with dead blow mallet to allow taper and spring pre-load to perfectly center barrel.
11. Cut off barrel and cut clean and bur free. I use my crowning tool (CERMET - high positive) and cut at 2000 RPM. For a mirror finish and no bur!
12. Indicate bore and grooves within a 0.001.
13. Insert Gritter rod with proper bushing (weighted to load - I agree) and indicate bore. I measure the reamer and determine where the bushing area will be positioned within the chamber - this is the critical dead "ZERO" location that needs to be verified and indicated to "ZERO" when done. High pressure coolant is turned on which fills the barrel and the Gritter rod is walked in while spindle is running at 100 RPM. Use Bump chuck to center barrel. You will see everything with in barrel! Continue to use bump chuck- look at end of barrel, look at runnout of bushing finish area and walk rod into bore 6-8" past finished throat area. SO........we now have the bushing area "DEAD ZERO" , the end does not matter (we will drill/bore) and the bump chuck was used to make sure everything ahead of freebore is zeroed. In summary, Muzzle is perfectly centered to spindle (spring loaded spindle thingy), throat area and 2-6" towards muzzle are zeroed.
14. Choose action type - Press go and machine entire Tenon (drills for chamber needed, pre-bores (straight -no taper) chamber, thread.
15. Insert reamer - High pressure coolant on and finish last 0.10" using reamer.
16. Check headspace.

First barrel takes 1 hour-15 minutes.....second, third etc take 30 minutes each

Side note high pressure coolant allows going almost to finish depth without cleaning. High speed steel reamers are run at 350 RPM and carbide at 1050 RPM! Reamed chambers must roughed up in bottle area due to extremely polished finish.

I will post some pics if interested.
Click to expand...


I would like to see some photos of the tooling and "spring loaded spindle thingy" also how do you seal the spring loaded spindle thingy so it doesn't leak the high pressure coolant? Ian
 
TRA said:
Sounds as if someones goats are loose again.

.
Click to expand...
TRA, from reading your posts I can see where you could benefit by taking the advise of some of the gunsmiths like Mike Bryant and Butch who build winning rifles for a living. But, for the life of me I can't see where you deserve it!!!
 
JonathanK said:
I am fairly new to doing chambers in the headstock and this is what I have ran into in dialing in a Bartlien Barrel. I have indicated the muzzle with a range rod to .0001 and I indicated 1 1/2 in on the chamber end with a DTI to .0001. When I back my DTI to where the chamber will start I get .0006 runout. When I dial in both spots in the chamber end (where the chamber will start and 1 1/2 in. in) I get .025 runout at the muzzle. I know I can only use two points to go off of but not sure which two will be best......
Thanks,
Jonathan K
Click to expand...

I presume 1.5" in is about where the throat would be. There are two cases to consider:

Case 1: The grizzly rod bushing is placed at a point 2.5" in, that is an inch past the throat. If runout at that point is also within +/- .0001, I'd machine the tenon and index the barrel blank to point up when the receiver is screwed on, then go ahead and chamber it however you want to.

In theory drilling and preboring before reaming would be the best approach, but with the bore from the breech end to an inch past the chamber within +/- .0002" I don't think it will make a difference.

Case 2: If, on the other hand, measuring an inch past the throat shows misalignment, I'd realign it so the two points, throat and an inch beyond, are dead nuts, cut and thread the tenon indexing the barrel to be up when the receiver is screwed on, drill, prebore, then ream.

Fitch
 
Thanks for all the good input....I going with Mike Bryants way as indexing would be a real pain with this glued in action
Awesome thread, Thank You all!!!
Jonathan Kuykendall
 
Without even reading any, I figure this must be a really good thread. 13 pages on chucking a barrel! :D
 
JonathanK said:
Thanks for all the good input....I going with Mike Bryants way as indexing would be a real pain with this glued in action
Awesome thread, Thank You all!!!
Jonathan Kuykendall
Click to expand...

Jonathan, as you're finding out when it comes to fitting a barrel, there is more than one way to do it. Read Gene Beggs method on another thread and you'll find another way of accomplishing the same end. It doesn't mean that one way is right and one way is wrong, it's just different. It all comes down to the fact there is only one measurement that makes a difference when all is said and done when it comes to competition rifle shooting, that's how the barrel shoots on paper. The job of the gunsmith is to do his best to make sure that you have the fewest reject barrels as you can.

I had a rail gun barrel one time, that I chambered by indicating the barrel in at the projected throat, and when I was through with the chamber, the throat was obviously off center when looking at it with a borescope. I cut the threads off and redid it, still the same result. Finally said the heck with it and ran the reamer in for the whole chamber without drilling and boring, the throat was in the center. I took it to New Braunfels to a nationals type match they were having there that weekend and shot about a .374" 200 yard 10 shot group with it in some pretty tough conditions. The barrel was a shooter, but it wouldn't have been with the throat off center. How it shoots, is the only measurement that actually matters. How you get to that point is immaterial.
 
You must log in or register to reply here.
Back
Top