Neck thickness measuring tool?

[TrxR]

I just recently ordered a neck turning setup from PMA Tool but am now realizing that im going to need something to measure the thickness of the necks. What do you guys recommend ? Mitutoyo ball mic like the one from K&m , the Sinclair/starett? Or something with a mandrel and dial gauge?

Thanks.

 

[Bob L.]

I use the K&M and have been well pleased with it.

 

[mikecr]

You need a micrometer with a ball anvil to measure spot thickness (forget mandrel types).
I use one of these: https://www.sinclairintl.com/reload...r-digital-case-neck-micrometer-prod38161.aspx
I consider it the best, but it's no longer available..
They still have this: https://www.sinclairintl.com/reload...r-starret-case-neck-micrometer-prod38096.aspx
I had one in the past, works good.

 

[Dud]

A ball micrometer, you can find a cheap one that will do the job if you can read a vernier.

Go for the kind with the little clutch thimble on the end that gives you consistent force during measurement.

I don't see a need to go fancy.

 

[laveritt]

Mitutoyo Ball Micrometer 115-313.

 

[Straightshooter1]

I just recently ordered a neck turning setup from PMA Tool but am now realizing that im going to need something to measure the thickness of the necks. What do you guys recommend ? Mitutoyo ball mic like the one from K&m , the Sinclair/starett? Or something with a mandrel and dial gauge?

Thanks.

You'll want to go with a ball micrometer for sure. I got one that was recommended to me as it was inexpensive and accurate. So I got this one and tested it for accuracy against a couple of very expensive ones from a machine shop and it was consistently equal to them:

https://www.amazon.com/gp/product/B01524DDIO/?tag=accuratescom-20

 

[jepp2]

Mitutoyo Ball Micrometer 115-313.

That is the one I use, but there are times I wish I bought the modified one from K&M.

 

[Jdne5b]

+1 for the K&M modified.

 

[tmwinds]

You'll want to go with a ball micrometer for sure. I got one that was recommended to me as it was inexpensive and accurate. So I got this one and tested it for accuracy against a couple of very expensive ones from a machine shop and it was consistently equal to them:

https://www.amazon.com/gp/product/B01524DDIO/?tag=accuratescom-20

I have this identical mic. It has served me well. Don't forget to get a stand for it unless you have three hands.

 

[mikecr]

There are 3 issues with the non-purpose-built MICs.
#1 no case mouth stop to set depth of neck measure.
#3 the ball anvil is not adjustable to the spindle face.
#2 no purpose built stand.
These issues can be solved, but you'll have to do it yourself:

 

[TrxR]

#1 and 2 are easy enough to work around but why is #3 important ?

There are 3 issues with the non-purpose-built MICs.
#1 no case mouth stop to set depth of neck measure.
#3 the ball anvil is not adjustable to the spindle face.
#2 no purpose built stand.
These issues can be solved, but you'll have to do it yourself:View attachment 1125044

 

[mikecr]

The merchandising hook with the K&M is the tapered spindle. This so you can sneak into the donut area nearest neck-shoulder junction. But it cost $175 and still has no stand and no case mouth stop..

With simple adjustment of the ball anvil height to spindle face, you don't need a taper spindle.
This adjustment will sneak into anything:

 

[TrxR]

The merchandising hook with the K&M is the tapered spindle. This so you can sneak into the donut area nearest neck-shoulder junction. But it cost $175 and still has no stand and no case mouth stop..

With simple adjustment of the ball anvil height to spindle face, you don't need a taper spindle.
This adjustment will sneak into anything:
View attachment 1125059

Where does a person find something with adjustable anvil height?

 

[wkdickinson]

When do we start the discussion about what point on the neck you measure? Seriously?

 

[wkdickinson]

When do we start the discussion about what point on the neck you measure? Seriously?

The reason I asked that question, beyond my concern for "picking the fly sh_t, out of the pepper", as one of my old bosses used to say, is:

1. By using a ball mic you get a point measurement. A bullet has a long, flat surface.
2. The neck of the case is long and flat.

Hence, why not use a "tubing" mic, that will give you the thickness of the neck, over the length of the surface the bullet engages it?

 

[michaeljp65]

The merchandising hook with the K&M is the tapered spindle. This so you can sneak into the donut area nearest neck-shoulder junction. But it cost $175 and still has no stand and no case mouth stop..

With simple adjustment of the ball anvil height to spindle face, you don't need a taper spindle.
This adjustment will sneak into anything:
View attachment 1125059

Hey Mike, i have that exact same Sinclair mic and i tapered the end on a bench grinder just like the K&M one. I also made a case stopper like on yours. although not as good as yours as im a shithouse handyman, but it works. I think it was a post of yours i saw many years ago showing it.

 

[Dud]

A micrometer usually has a precision of +/- 0.001" but that's over a 1.000" range.

When you are measuring 0.010-15", the precision is going to be much higher because the range is so small and the measurement is so close to zero where you can adjust the vernier for perfect measurement.

It's really easy to test a ball mic in that range with a feeler gauge so you can even calibrate it at your desired measurement if you're that anal.

This applies to all micrometers from fancy Swiss and Japanese to cheapo Chinese no names as long as it's not absolute garbage with poorly ground anvils that were dropped a few times.

Of course there is nothing wrong with using an expensive Mitutoyo but if you're skimping somewhere else to go fancy there, you're not getting the most out of your money.

If you need to detect a doughnut, get a plug gauge.

Of course a neck should be measured several times in several places to see what is going on but that raised anvil will let you measure closer to the shoulder.

I see this tool as more of a way to confirm thickness after I size, ream and neck turn new brass.

 

[Tim Singleton]

Sacrifice a piece or two by seating a bullet and micing the loaded round
Only way to go
imo

 

[mikecr]

Where does a person find something with adjustable anvil height?

Right now, Sinclair offers this: https://www.sinclairintl.com/reload...r-starret-case-neck-micrometer-prod38096.aspx
It's nice & you can drop washers over the anvil for a case mouth stop.

why not use a "tubing" mic, that will give you the thickness of the neck, over the length of the surface the bullet engages it?

Won't work because necks taper in thickness, and it's not linear. You need point measure around necks and at a couple depths.

i have that exact same Sinclair mic and i tapered the end on a bench grinder just like the K&M one.

You didn't have to mess with the spindle. Just adjust anvil contact to spindle as pictured.

Sacrifice a piece or two by seating a bullet and micing the loaded round

I agree that field thickness needs to be verified. Sized down necks are thicker than expanded necks. So with turned necks as new & ready for bullet seating, they will thin a hair more where a seating bullet expands. But if my goal is 0.01200" neck thickness, and calculated with seated OD ends up 0.01197", I'm not concerned with that. This is predictable as well, right up front. The distance sized up/down is applied to thickness radially.
I also use my neck mic to see and cull new brass by thickness variance. That variance runs full length of cases, and is the root cause of runout as brought on by sizing cycles. Having a mouth stop is critical here, because of the thickness taper with new necks. Apparent variances will go all over hell if not setting a depth datum.

 

[spclark]

I use one of these: https://www.sinclairintl.com/reload...r-digital-case-neck-micrometer-prod38161.aspx
I consider it the best, but it's no longer available.

Same here.

Glad I asked for one years ago when my wife asked me for my Christmas list.