Range Rod or Indicator?

B

Bill in AZ

Guest
I looked around her a bit but did not see this topic.
Brand new to chambering and have heard of the "Range Rod" method of centering the barrel bore as well as using an indicator to get alignment. Seems to me either will get you close, but which is better for a guy with a limited shop?

Also how do I ge the muzzle end "centered"? My lathe does have a spider on the left end of the spindle, but do I center it here based on the OD of the barrel, or somehow get an indicator out to the muzzle to go off bore?
 
First, slug the new blank after cleaning and lightly greasing the bore. Very rarely, but sometimes, you will find a bore that is oversized somewhere between the breach and the crown. Or, the barrel may have a larger bore toward the muzzle. This can cause mid-bore coppering. A barrel that coppers mid-bore will never shoot accurately.

Then, determine the length of the blank to get the weight you need, cut the blank to that length plus a bit. If you closely dial in the location of the chamber neck, and the bore, not the OD, at the muzzle, that is as close as you can get it.

.
 
An alternate theory is that the best you can do is to dial in the future location of the neck and a little ahead of that point, in hopes of starting the bullet 'straight' into what is never a perfectly straight bore. Letting the muzzle just point wherever it ends up during the aforementioned alignment (the headstock support can still be used). I use a range rod for setup (no indicator I know of will reach that far into an uncut barrel) and an indicator to check all final concentricities, so I recommend having both anyway - experiment and see what theory you come to subscribe to.

If you search for 'Gordy Gritters' or 'Gordy's Method' you can find more information on what I'm trying to describe.

GsT
 
Gentlemen, Thank You for your replies. I will do more research, but can see this is a task with more than one approach and I will try both to see which I find meets my requirements.

I have a Mike Rock barrel blank from 2008 in 7mm that I had planned to build up a 280 Ackley rifle with but since lost interest. I have a PTG reamer for this cartridge and believe I will cut my first chamber with this reamer and see what happens. Still have a lot to learn and everything to experience! I read a couple books and also watched the Grizzly video (so I know almost enough to get in trouble!).
 
Gordy has a chambering video on Grizzleys website where he chambers a barrel using the Grizzley indicator rod and bushing setup. Many guys use this method. There are also guys that use deltronic pins to indicate a barrel in and there are the guys that use a pin in the muzzle and a interapid long test indicator in the throat of the barrel and call it good. If you'll buy all the stuff to try the different methods you will figure out which is the best in your mind and that's all that matters. There are very successful shooters that use one of the three methods and there are other successful shooters that use all three. A good floating reamer holder and a snug bushing fixes a lot of errors, even the mental ones floating around in the minds of some very experienced gunsmiths that say stuff like my way is best. The best way is dictated by how crooked the blank is, after you chamber some you'll understand that.

Have fun with it.
 
OP
There are range rods, indicator rods and then there are gordy rods, sometimes called Grizzly rods. Each different than the next. The range and indicator rods are similar but still different. I use a range rod on a new barrel to dial in a rough start. I then go to the grizzly rod, followed by a dial indicator on the throat, Go to PTG web site and read about each of the tools in the product description. Lee
 
Some guys make very long-reach extentions for their indicators, and insist that the dial still reads true! :confused:
 
Good information guys and much appreciated! I like to hear your opinions and references.
 
does it really matter

Fussy1 said:
Some guys make very long-reach extentions for their indicators, and insist that the dial still reads true! :confused:
Click to expand...

if the needle doesn't move?? Is .0001 going to make a difference?? I don't think so.
Were not looking for a "measurement" just no runout.
Saying that, I bore and indicate with a "true" indicator.

Richard
 
I start out with my tenth DTI on a "Grizzly Rod" riding where the throats will be. Then I stick my long reach half-thou Interapid DTI to the future throat location to verify. I almost never need to make adjustments. I still have every caliber range rod but I haven't used them in years. They are not repeatable.
 
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I got gauge pins

I use. I indicate both ends to as near zero as I can get, cut the tenon and then chamber. I know there are lots of opinions on cambering but I have found my method works ok for me. I once saw a well respected Gunsmith chamber one of my barrels with the muzzle end in a sleeve inside the long spindle and the breech end held in a 6 jaw chuck. Ain't the way my head says to do things but the rifles he made shoot the very best and have set records.

Pete
 
Fussy1 said:
Some guys make very long-reach extentions for their indicators, and insist that the dial still reads true! :confused:
Click to expand...


True is not as important as zero indicator movement.

Adjust till it sit on a hash mark with no movement.

I have some older incredible indicators.

Many have no actual indication on them of the value of the division.

A few are better than 1/100,000 of an inch.

I have never seen any of them for sale in 45 years of watching.

I have a dial caliper that uses a dial indicator on the moving side.

You can adjust it using the dial on the caliper and then lock it and use the dial indicator for inspection work and checking to its limit.
 
I would be afraid to even try to use a 1/100,000 indicator; would like to see one, though. What are they used for? What did they cost?
F1
 
All Good

This is all good information. I have a PTG range rod on the way and as soon as I find my DVD with Gordy chambering a barrel I will watch it one more time, see what more I need in tooling and then soon get the barrel in the 4-jaw chuck and see how well I can get it dialed in on the rod then pull the rod and indicate off the bore and see if it agrees. Not going to rush into this.

My lathe spindle has four screws on the left end (muzzle end of barrel if cutting a chamber) to align the barrel on the opposite end you are working on, but not sure how I will get an indicator rigidly mounted to indicate off the range rod out off the lathe that far. Hopefully my magnetic base with its jointed arms is repeatable at this extension.

Thanks again guys!

Bill in AZ
 
i will never understand why anyone would indicate a spot twenty something inches away from the business area. your just indicating in one spot at the chamber by doing so.. i just dont get it! LOL. everyone's brain works differently i guess. lee
 
Actually, I think you would be indicating

2 spots using gordys method. The first is the very back of the bbl and the other is where the throat would be. The thought being the bullet has a perfectly straight shot starting down the bbl. And let the muzzle runout be what it is.

I don't like that either. I indicate the throat and the muzzle. You can only indicate 2 spots on the bbl
either throat crown or back of bbl and throat. Well, I guess there can be three, back of bbl and crown, turning on the steady rest. But you can't indicate three spots, otherwise your bending the bbl.

Richard
 
There is only going to be a few thousants of curvature over the entire twenty-something inches if the barrel. The worst barrel I ever measured only had 0.013" of curvature. Sectioning that into inches of barrel that is about 0.0012" of curvature in the chamber area.

It is much more important for the barrel muzzle to point in the same direction as the entire gun than to have this 0.0012" aligned with the assembly. Besides good machining practices assures that 0.0012" is going to be bored out before the chamber is reamed.

It IS IMPORTANT for the chamber neck and leade (freebore) to be in perfect alignment with the bore at the point where the bullet enters so one of those two spots indicated must be the chamber neck. Besides, using a rod that extends several inches OUTSIDE the barrel as the area to be trued is ridiculous.


..
 
JerrySharrett said:
There is only going to be a few thousants of curvature over the entire twenty-something inches if the barrel. The worst barrel I ever measured only had 0.013" of curvature. Sectioning that into inches of barrel that is about 0.0012" of curvature in the chamber area.

It is much more important for the barrel muzzle to point in the same direction as the entire gun than to have this 0.0012" aligned with the assembly. Besides good machining practices assures that 0.0012" is going to be bored out before the chamber is reamed.

It IS IMPORTANT for the chamber neck and leade (freebore) to be in perfect alignment with the bore at the point where the bullet enters so one of those two spots indicated must be the chamber neck. Besides, using a rod that extends several inches OUTSIDE the barrel as the area to be trued is ridiculous.


..
Click to expand...
"Good machining practices" does not agree with your theory. Just how did you measure the bore in order to take a straightness measurement? Just an observation but all these declarations of fact seem to be based on a 6ppc cartridge and short barrel. What some may claim to be absolute, has very little bearing when chambering, lets say, a 338L or a Cheytac with a 40 deg shoulder and a 3' barrel.
 
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