Test Dial Indicator for Chambering

[VA_XTC_Shooter]

I did a little searching and it appears some of the preferred indicators with the long stem are no longer available. I found a few that I think will fit the bill, but wanted to get some input to see if I am missing something with these before I pull the trigger.

Amazon because I have a nice gift card that will cover the cost.

Mititoyu 513-504T

Mitutoyo 513-412-10T

There are quite a few long indicator tips available as well. Does Mititoyu use M1.6 threaded tips?

 

[tac284]

I personally use the 513-504’s. Depending on you’re dialing method for indicating barrels the round body of the 504 will allow you to insert it farther inside the barrel, say if you are pre-boring and then wanting to check at the throat and then just past you would be able to insert the body into the drilled hole and then check. Now depending on cartridge you may need the longer stem, and I do believe they are 1.60mm x .35 if i remember correctly.

I also have the Interapid 312B-15 (.0005) with the long stem. There is a generous amount of room between the tick marks so you can do a better job than .0005

 

[Danny1788]

Interapid 312B-15 (.0005) with the long stem this what i use as well

 

[xr650rRider]

This tip fits the 513-504, it allows nearly a 4" reach but I prefer the Interapid 312B-15 most of the time.

 

[VA_XTC_Shooter]

What is the rule of thumb for accuracy change when adding a long stem to a short stem indicator? Does the accuracy go from 0.0005 to 0.0015 or worse? To me, that would negate the benefit if you are no longer under 0.001 accuracy.

Also looking at the
Brown & Sharpe - model 7035-5

 

[xr650rRider]

It becomes less sensitive with longer tip and for the Mititoyo being .0001" indicator with .0002" accuracy, it becomes the ratio of 2.675/0.7 * .0002" or .00076" accuracy. But your using the indicator as a comparator, one land vs another. When it is bouncing in same spot from one groove to the next, you can't technically say it's exactly 0 or .0001" but everyone does.

 

[swd]

The Interapid 312b-15 is probably the most popular indicator. It's easy to resolve finer than the .005" marks. Expensive but worth it.

 

[VA_XTC_Shooter]

Thanks for the input, I ended up going with a Brown & Sharpe - model 7035-5, got a great deal on it. The 1-7/16” tip should be plenty for my 6BR. Also think the wide spacing between the 0.0005” tick marks will allow a little more scrutiny on runout.

then again, I may be totally wrong, lol

 

[Dusty Stevens]

Bought new 2 weeks ago

 

[escopeta]

Set up I made for chambering on my Grizzly gunsmith lathe. Large dial Federal 3” travel indicator and homemade stop that clamps on the quill. Very reliable and repeatable.
Also tool I made to check headspace with go gage.
Have different sizes for different tenons. Use large flat indicator tip and zero on flat surface.

 

[escopeta]

Forgot to ad that I use a large c-clamp across the bed as a positive stop for the tailstock so I can move back for measurements and cleaning.

 

[butchlambert]

Forgot to ad that I use a large c-clamp across the bed as a positive stop for the tailstock so I can move back for measurements and cleaning.

It is easier for me to lock the carriage for a positive stop.

 

[escopeta]

Don’t use carriage, only tail stock and don’t have carriage lock.
Use Gritter’s rod and close fitting bushing about.0002” under and indicate area where bullet will be when chambered on the forward spider and plug gage on outboard spider for zero.
Rough drill chamber then bore before using reamer. Get about.0002” chamber runout which is about all the lathe will do.
What I do for my F Class shooters that may want to change barrels in a match with little scope adjustment.
Know there are many ways to accomplish the task, just what I use.

 

[jackieschmidt]

I use the 513 504 series, because it suites the way I chamber barrels perfectly.

 

[Greg Y]

I run a 312-b as well. I also have a Browne and Sharpe 7033-5 (.00005") for when I want to drive myself nuts. That little monster only has like .008" travel and will pick up when you put your hand on an 8" chuck.