Indicating a barrel blank...

G

gpoldblue

Member
What is the correct way to indicate a barrel blank in a lathe...off the lands or off the grooves? I appreciate your advice. Thanks to all who answer.
 
If 100 different people reply, you'll get 100 different replies.
 
gpoldblue said:
What is the correct way to indicate a barrel blank in a lathe...off the lands or off the grooves? I appreciate your advice. Thanks to all who answer.
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On the breech (chamber) end indicate on the lands (the small diameter) since that is where your reamer bushing will ride. On the muzzle end when crowning indicate on the grooves since that is the last part of the barrel the bullet sees especially if you put a bevel on the crown.

In actuality, if a barrel is rifled correctly it doesn't make a difference since all the grooves should be the same depth and the lands should be the same height. Occasionally you will find a barrel that isn't exact. Does that make a difference, dunno!! But if you did find one that was different by more than 0.0002" or so, I'd send it back.
 
jackie schmidt said:
I agree with Jerry........jackie
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So would you use or recommend a "range rod" or similar as sold by PTG ??
I am just getting going so forgive me if this is a silly question, but when using the range rod method if the tail stock is out of alignment does it make a difference ????
Thanks
Matt P
 
Matt P said:
So would you use or recommend a "range rod" or similar as sold by PTG ??
IMatt P
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Not on my barrels. When you are indicating with a range rod you are indicating OUTSIDE the barrel. Not the best, IMO. I like for the indicator probe to contact in the bore at the exact location that the chamber neck meets the barrel bore.
 
Grooves. The groove is the major diameter of the bullet and is by far the majority of surface of the inside of the barrel.
 
Butch Lambert said:
Well,
I indicate the grooves and am checking the lands at the same time.
Butch
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Well, actuchalley, the lands and groves ARE indicated together. It'd be kinda' hard to indicate a groove, then withdraw the indicator, cross over the land, indicate another groove and so on. But if Butch and Mike insist, I guess I'll try it!!! Anything to keep the peace this Winter.
 
Jerry,
I took Jackie's advice and bought a 513-504 Mitutoyo dial test indicator. I indicate first with Deltronic pins on both ends. I predrill and then reach in with the Mitutoyo and indicate the grooves before taper boring. I like the Mitutoyo as the whole body will go into the drilled hole and you have a short stylus that will move from grooves to lands as you are indicating. I tried to do that with my long reach Interapid and just didn't like the way it jumped around.
Butch
 
JerrySharrett said:
Well, actuchalley, the lands and groves ARE indicated together. It'd be kinda' hard to indicate a groove, then withdraw the indicator, cross over the land, indicate another groove and so on. But if Butch and Mike insist, I guess I'll try it!!! Anything to keep the peace this Winter.
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Geez Jerry just use 2 indicators, one on the grooves one on the lands, that's why God gave you 2 eyes. Ha

James
 
Chisolm said:
Geez Jerry just use 2 indicators, one on the grooves one on the lands, that's why God gave you 2 eyes. Ha

James
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But, James, I only have one that works and it isn't much to brag about.

Butch, if you would use a stylus with a ball diameter of 0.080" or 0.093" they will not jump around. I have trouble with the Mitutoya in getting it to fit in the drilled hole without rubbing on the body. Whatever works, right.

In the olden days in the "old shop" we used a nail in a stock. But the alignment of a catapult arm was not that critical.
 
Jerry,
I didn't have any trouble with it. Maybe I'm more experienced putting something small in a big hole. Ask Jackie how he gets his in.
Butch
 
Hi
Using the Gritters method, does the tailstock alignment become more critical ?? I doubt the chuck holding the rod is in perfect alignment ??? Am I missing something ( I think I am ) ??
Matt P
 
Butch,
Would you recommend the 513-504 or an indicator with a longer point for longer cartridges other than br cases?

Thanks
Kyle
 
Matt P said:
Hi
Using the Gritters method, does the tailstock alignment become more critical ?? I doubt the chuck holding the rod is in perfect alignment ??? Am I missing something ( I think I am ) ??
Matt P
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Matt, I've used the Gritters method and found no need, no gain, no reason for careful tailstock alignment. Didn't even check it.

I chuck just 1/8" or so of the tail into the chuck, it's just hanging there.

sometimes I hang a weight (dead center) on the rod just to induce a nice downward pressure. Kinda' like the spring pressure on the indicator stylus.

al
 
Jerry,

In order to reach into the chamber, neck, leade portion of the barrel to be chambered, you are using a long stylus on your indicator? Doesn't this take some of the sesitivity, or resolution out of the test indicator's reading?

Paul
 
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