neck thicknesses

cajun said:

It's not the precision. Your trying to measure a curved surface with a flat object. The ball mic is made to measure tubing and round objects.

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When I get .0135-14 with calipers, that gives me an OD of loaded bullet .312. Measured by caliper and Mitutoyo micrometer. Like clockwork. So, my relative measurement of the case neck thickness with calipers translates to a direct measurement of the OD.

If for some reason the case neck thickness was required to fly to Mars, the Aerospace industry wouldn't like my way, but alas, handloading ammunition is never needed to be to a degree as Aerospace. I can't think of one instance a .0005 tolerance is needed to be hit exactly in handloading.

What cajun said. It's what I said above, too. Calipers are completely inappropriate for performing this measurement due to the geometry of the measuring faces of the caliper.

Yeah, we probably all do it now and again, but if you need an error-free measurement calipers are the wrong tool. When you're setting up the dims for a custom chamber you want an error-free measurement.

ntsqd said:

What cajun said. It's what I said above, too. Calipers are completely inappropriate for performing this measurement due to the geometry of the measuring faces of the caliper.

Yeah, we probably all do it now and again, but if you need an error-free measurement calipers are the wrong tool. When you're setting up the dims for a custom chamber you want an error-free measurement.

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They work just fine for this operation.

If you're happy with the built-in error I know that I'll never change your mind.

ntsqd said:

If you're happy with the built-in error I know that I'll never change your mind.

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It's not an error if it works and works consistently for a desired result.

It is still a known error.
It's not consistent, that's part of the problem with doing it that way. Each different ID is going to yield a subtly different measurement. The whole problem isn't just this small error, it is that eventually you have a stack of them and you don't know how far astray they've led you until something doesn't work like it was expected to. Ask any Engineer, Designer, or Draftsman about "Large assembly tolerance stack analysis" if you want to give them nightmares.

Up to the person doing the work to decide if that error is acceptable or not. When I might be laying out a custom reamer it would not be. Not even close. If I'm looking at a new lot of brass and deciding whether or not to run them thru the neck turner, then that error isn't too important because the turner will correct it. But when I set up the turning tool it is hugely important so that I get the expected neck thickness.

ntsqd said:

It is still a known error.
It's not consistent, that's part of the problem with doing it that way. Each different ID is going to yield a subtly different measurement. The whole problem isn't just this small error, it is that eventually you have a stack of them and you don't know how far astray they've led you until something doesn't work like it was expected to. Ask any Engineer, Designer, or Draftsman about "Large assembly tolerance stack analysis" if you want to give them nightmares.

Up to the person doing the work to decide if that error is acceptable or not. When I might be laying out a custom reamer it would not be. Not even close. If I'm looking at a new lot of brass and deciding whether or not to run them thru the neck turner, then that error isn't too important because the turner will correct it. But when I set up the turning tool it is hugely important so that I get the expected neck thickness.

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There would only be an error if my loaded neck diameter was above my target .312-.3125". When my caliper reads a case neck thickness of .0135-.014" I know that will give my loaded dia. at the neck .312" with a positive tolerance of .0005" or .3125" consistently for each round I make. I have hundreds loaded up right now with that target diameter. So, you can't say my process isn't consistent because every single round made tells me I am. When they don't read .0135-.014 then that OD diameter shows me. It really is that easy.

ntsqd said:

If I understand your question correctly, you need a tool like one of these:

Neck Turner Builder | Neck Turning Tools | Precision

Neck Turner Builder | Neck Turning Tools | Precision Micro Adjustable Neck Turner Tool & Best Neck Turning Tools for Accuracy

kmshooting.com

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Perhaps my question was not clear. I have the K&M neck turning tools and have used them successfully for many years. What is not clear is how one sets up the cutter depth to taper from .0135"-.014" over the length of the case neck. Thanks again, Ed

Lionel Boyd Johnson said:

Perhaps my question was not clear. I have the K&M neck turning tools and have used them successfully for many years. What is not clear is how one sets up the cutter depth to taper from .0135"-.014" over the length of the case neck. Thanks again, Ed

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You can't cut a taper on the K&M tool. Chambers are tapered a bit in the neck area from base to mouth. You turn a consistent thickness with the tool.

Perhaps I misunderstood what MagnumManiac said: "MagnumManiac: "To make the brass fit, it needs turning to be .014" at the upper end or .0135" at the lower end." I took that to mean a taper from the upper end to the lower end. I guess he meant the acceptable range is .014" to .0135".

Lionel Boyd Johnson said:

Perhaps I misunderstood what MagnumManiac said: "MagnumManiac: "To make the brass fit, it needs turning to be .014" at the upper end or .0135" at the lower end." I took that to mean a taper from the upper end to the lower end. I guess he meant the acceptable range is .014" to .0135".

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I believe it's not a "placement " only minimum and maximum, ie upper and lower. Not a mouth measurement and neck shoulder junction. I could be wrong about his answers?

For those using a mic instead of a caliper you do what works for you? What i will say about a caliper is, it has a slight "wiggle " compared to a mic by design. I've dealt with many in auto mechanics.

Brathany said:

There would only be an error if my loaded neck diameter was above my target .312-.3125". When my caliper reads a case neck thickness of .0135-.014" I know that will give my loaded dia. at the neck .312" with a positive tolerance of .0005" or .3125" consistently for each round I make. I have hundreds loaded up right now with that target diameter. So, you can't say my process isn't consistent because every single round made tells me I am. When they don't read .0135-.014 then that OD diameter shows me. It really is that easy.

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Re-Read what I said about where the inconsistency comes from, and about my never convincing you.

As I first read Magnum's numbers I thought at first that he was turning a taper and on re-reading it I convinced myself that it was a tolerance window, too.

ntsqd said:

Re-Read what I said about where the inconsistency comes from, and about my never convincing you.

As I first read Magnum's numbers I thought at first that he was turning a taper and on re-reading it I convinced myself that it was a tolerance window, too.

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I'm fully able to comprehend what I read the first time. You bring about a point that doesn't matter. Never in my shooting career did I have to consult an engineer, draftsman, or theoretic physicist to accomplish my goals. What inconsistency do you speak? .0005" tolerance? I'll accept that, my groups accept that too.

Lionel Boyd Johnson said:

MagnumManiac: How do you do this: "To make the brass fit, it needs turning to be .014" at the upper end or .0135" at the lower end."?

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I'll explain a little better, my necks are TURNED to give me neck wall thicknesses of the above number. I measure the neck thickness with a ball end tube mic that reads to .0001" accurately.
The reason I say .014" at the upper end is because if it's thicker than this, clearance is reduced in the chamber.
You cannot GUESS doing this, neck turning is a precise operation and if done sloppily you have essentially wasted your time.
For example, if I do not turn my Winchester ww-super brass in 264WM for my custom LR rifle, the necks are so thick it will raise pressure to the point it will blow primers. There just isn't any room for the neck to expand into. This chamber is NOT a neck turn chamber by design, just my spec based on the brass neck thickness after it is turned to be .014" thick.
Hope this makes sense now.

My Remington and Norma brass in 264WM only need a skim turn to clean them up to fit this chamber, so choose your brass wisely when designing it.

Cheers.