indicating in barrel

[wapiti25]

Gordy, Whose indicator are you using to reach up the bore. I'm looking for model number. I can only get .800 with my interapid without loosing resolution by using the long tip.

Wapiti

 

[butchlambert]

Wapiti,
Try the Mitutoyo 513-504. It has a long slim body with a .625 probe. If you predrill, it will fit in the hole and the short probe is easier to indicate with. I have a 1.5" probe on my Interapid, but I'm not confident in it. It just seems to flex too much.
Butch

 

[wapiti25]

Thanks Butch, I will check into the Mitutoyo. I love the Interapid but I use the .8 tip almost all the time, they are "work horses".

 

[Rustystud]

Butch and Blair:

It seems this topic goes round and round.

The end result is what matters. Both of you can and do build rifles that shoot better than most shooters can hold.

Many folks don't understand that changing the load on the bearings will change the readings.

Temperature will change the readings.

Just removing and re indexing you will enconter different readings.

The end result of a barrel being spun in the spindle bore without any indicated runout with a tent indicator is what it is all about.

Nat Lambeth

 

[zp3design]

Has anyone ever made or tried a bushing that rides in the grooves instead of on the lands...more difficult to make for sure...just curious.

 

[butchlambert]

I believe that Turk Takano did it years ago when he worked at Shilen. Said there was no advantage and as he had to make them on a tool and cutter grinder, it was very time consuming. Remember, you would need several sizes for each bore size. If you have ever carefully indicated the bore and grooves, you will find the groove depths can vary.
Butch

 

[drumcorpschamp]

Chambering my first barrel. I am a Toolmaker by trade, lathe set-ups, indicating and holding tenths are the norm for me. Doing gun work is not.

The chamber end is being held by a six-jaw adjust-tru chuck. Have a 1/8" aluminum ring around the barrel that I am clamping on. Muzzle end is held in a spider at the back end of the spindle.

Deltronic pin in the muzzle end with an indicator on it. An indicator with a 2 5/8" probe on it at the chamber end. Indicated the muzzle to zero and indicated the chamber end at zero as well. The indicator tip was 2.100" inside of the chamber end of the barrel.

To check my work, I inserted a reamer blank into the chamber end (yes it fit very closely) and 2" from the chamber end of the barrel I read .0015" runout. The runout decreased as I moved the indicator closer to the chamber end. I looked through the barrel while spinning and it looked like I had a very slight bow in the bore.

Did the 2 indicator method on the reamer blank while tweaking the muzzle end. Got zero runout and re-indicated zero 2.100" inside the chamber end. The result of all of this is that the muzzle end now runs out a total of .022". I figure that I'll index the barrel to the receiver so the bore is up @ 12 o'clock.

My question after all of this typing is.......is .022" total runout at the muzzle end too much? A little quick math in my head tells me that all things being equal and relative, my point of impact will be about 2 1/2" to 3" high at 100 yards from what would be considered "normal".

Butch, Nate, Gordy......anybody else?

Thanks,
Jerry

 

[butchlambert]

Jerry,
It may be easier for you to understand than others. Go back to an indicator on both ends indicating the Deltronic pins. Just think along with me. Predrill your chamber and now reach in and indicate the area that will be your throat. Taper bore to that point to about say .080 short of the shoulder and then finish ream. Would your chamber now be coaxial to the bore at the throat? Yes it will and your muzzle will be on the same axis. When you prebore the chamber you will not have any runout at the back of the chamber and the bullet is still looking at a nice coaxial throat.

 

[Robert]

High level discussion...

'Chapeau, Messieurs'...

R.G.C

 

[drumcorpschamp]

Butch,

Finished the chamber today. I decided to hold my course with clocking the muzzle up as the tenon threads were already completed at the time of my posting yesterday. (The thread fit was very close and I didn't want to re-skim them after changing the setup.) Appreciate the input and I'll go that way next time.

I am absolutely tickled with the results of my chambering. I wrote a program off of the reamer dimensions, stopping at the shoulder/neck junction. Offset the boring bar -.010" in X and +.020" in Z. Left the bushing off of the reamer and the result is dead zero indicator readings from lands and grooves, 1deg 30' lead, throat, neck...yada.....yada. Headspace turned out about +.001" on the Go gauge as well. Happy camper.

Next is lop off some from the muzzle end and give it a nice, sharp crown. Good thing I'm not keeping track of my hours on the project! At shop rate, I'd be up to about a Bazillion dollars for a Rem. 700.......Just sayin'

Thanks,
Jerry

 

[butchlambert]

Going to the trouble to prebore properly makes a tight fitting bushing a problem for a good chamber. I understand why some folks like the 2 indicator method, but they are not really doing anything different than indicating the throat and preboring to that point.
Jerry I believe you will get the most out of your barrel job. I believe the only real problem to indicating one end is the odd chance that you would have to change a barrel during a match. Sometime you may have trouble getting on paper and shooting your group in 7 minutes. Now if you have shot both barrels and keep good notes, that is not a problem.
Jerry if I didn't have my own machines I wouldn't worry a bit about Dwight Scott, Billy Stevens, Mike Bryant, or a couple others doing my work. Just buy your barrels early and then your smith will have time to get you ready. DON'T wait until March to buy a barrel and expect a good smith to turn it quick.

 

[Rustystud]

Blair and Butch:

As we all know this subject has gone round and round for years and more years.

One thing Butch is saying is true, removing the bushing piloted rod and returning into the bore gives a different reading by a few tenths. But what he is not telling you is if your turn the chuck the new reading still indicates dead nuts if you don't loose your bearing load.

If Butch used his carriage as the base holder for his indicator and moves his carriage so the indicator leaves the bore and returns it to what he considers to be the same spot his indicator will too be off a few tenths.

Even variations in temperature can effect a reading by a few tents.

Land and grove diameter can vary due to barrel hardness, tool wear/geometry and a number of other anomolies.

We all want our rifles to shoot the best we can make them. Our methods may varry a little to alot. But the results for the shooter is the same a great shooting rifle.

Good Day and may we quit chasing our tails...
Nat