Virgin Brass and Projectile Measurement Tolerances

[Rommel Garcia]

Question for our experts here. The virgin cases I’ve measured are 260 rem Peterson and the bullet is Nosler ABLR 142gr. Here are the ES for each measurement.

Brass:
Length : .006”
Neck Diameter: .004”
Neck Thickness: .0035”
Weight: .8gr

Bullet:
Length: .0065”
Diameter: .0035”
Wright: 1.4gr

Are these ES measurements within acceptable tolerance? I’ll be shooting at least 600 yards and upto 1K.

 

[BenE]

Respectfully, check your measurements. I find it hard to believe you have bullets that are +/- 0.00175” off nominal diameter. Are you using a digital caliper? I can make those read anything I want +/- 0.0015” Check your measuring techniques and try again cause those numbers aren’t close to right

 

[Rommel Garcia]

I’m using a digital caliper and measuring the diameter of the bullet in the middle where it’s flat. I don’t squeeze/pinch the bullet that much. When it contacts that’s when I measure. I can re-measure. How do you typically do it?

 

[Tokay444]

Check the calibration certificate for your caliper. You might be surprised to find it has an accuracy of about +/-.002”. That’s .004” total.

 

[Rommel Garcia]

The one I have is the Mitutoyo brand. I still have the manual. Will check for calibration.

 

[Tokay444]

Yeah, it’ll be in that area. A caliper isn’t meant for fine tolerance work.

 

[BenE]

Applying constant and even pressure roll/rotate what is being measured. This will help eliminate error. Tokay444 is right, calipers get you close but not exact even for a quality brand like Mitutoyo

 

[BenE]

If you are measuring an X diameter and are off on the Z it will read a couple thou different

 

[Rommel Garcia]

Based on this certification it appears my
caliper error range is between -0.001 to +0.0005. This should be fine. Might be my method of measuring. Any thoughts on the brass measurements?

 

[ma smith]

“Calibrated Products” from Mitutoyo America - Mitutoyo

Mitutoyo America Corporation offers “Calibrated Products” that include an ISO/IEC 17025 Accredited Certificate of Calibration packaged with new Mitutoyo products. The Certificate of Calibration is fully endorsed and includes the […]

www.mitutoyo.com

 

[BenE]

At this point in your reloading journey….. safety is paramount. Squabble over bullet and brass consistency later.

 

[Rommel Garcia]

If you are measuring an X diameter and are off on the Z it will read a couple thou different

Z?

 

[Tokay444]

Based on this certification it appears my
caliper error range is between -0.001 to +0.0005. This should be fine. Might be my method of measuring. Any thoughts on the brass measurements?

Yes, at one diameter of 4mm.
Would you at all mind posting pics of how you're positioning your caliper jaws while taking the measurements?

 

[Doom]

So your Lee Perfect powder measure does good will ball powder? For $25-30 I’m strongly considering giving it a shot.

Question for our experts here. The virgin cases I’ve measured are 260 rem Peterson and the bullet is Nosler ABLR 142gr. Here are the ES for each measurement.

Brass:
Length : .006”
Neck Diameter: .004”
Neck Thickness: .0035”
Weight: .8gr

Bullet:
Length: .0065”
Diameter: .0035”
Wright: 1.4gr

Are these ES measurements within acceptable tolerance? I’ll be shooting at least 600 yards and upto 1K.

You are getting lost in the finer details of reloading for precision. As for your data, posting the ES is meaningless without knowing what the standard deviation and mean are. You're only giving us data based off 2 pieces.

On the surface you measurements don't appear correct. I would not expect the neck thickness to vary by 0.0035" in just about any brass that is from the same lot nor would I expect neck diameter to vary by 0.004". Is this as-received brass or have you sized it.

You also are shooting a hunting bullet. The AB is a great bullet but it is not a bullet most would choose for 1000 yds if precision is what I was concerned with.

 

[Tokay444]

A caliper is not the correct tool to measure neck wall thickness, because of the flat land on the blades. You end up with 3 points of contact rather than the 2 points the tool is designed to read from.

 

[Rommel Garcia]

You are getting lost in the finer details of reloading for precision. As for your data, posting the ES is meaningless without knowing what the standard deviation and mean are. You're only giving us data based off 2 pieces.

On the surface you measurements don't appear correct. I would not expect the neck thickness to vary by 0.0035" in just about any brass that is from the same lot nor would I expect neck diameter to vary by 0.004". Is this as-received brass or have you sized it.

You also are shooting a hunting bullet. The AB is a great bullet but it is not a bullet most would choose for 1000 yds if precision is what I was concerned with.

As Tokay44 mentioned caliper with the wrong tool to measure neck thickness. Neck tension matters more than neck thickness anyways o I think I’m just gonna skip measuring the neck thickness.

Brass is brand new ordered from Brownells.

 

[Rommel Garcia]

A caliper is not the correct tool to measure neck wall thickness, because of the flat land on the blades. You end up with 3 points of contact rather than the 2 points the tool is designed to read from.

This makes sense. What do younger to measure thickness?

 

[Tokay444]

A tube micrometer will give you better results.

 

[Evintos]

I’m using a digital caliper and measuring the diameter of the bullet in the middle where it’s flat. I don’t squeeze/pinch the bullet that much. When it contacts that’s when I measure. I can re-measure. How do you typically do it?

Tube micrometer for neck wall thickness, outside micrometer for bullet diameter.

If you really wanted to sort bullets though, the thing you should check initially is bullet base to ogive rather than bullet overall length. For that you'd need a bullet comparator.

 

[ma smith]

This makes sense. What do younger to measure thickness?

Neck walls aren't always single thickness, which is another part of the problem. They can vary around the mouth and along the length.

In general, for this work you need micrometers not calipers, and you need anvil-shapes that work with concave+convex shapes, not just flat surfaces.so there's both some basic tools and basic techniques involved that are worth brushing up on.

its worth reading some of the 6mm br .com articles if this stuff is all new.

alternatively, this vid of UR doing a/b comps maybe is useful?

 

[Rommel Garcia]

Tube micrometer for neck wall thickness, outside micrometer for bullet diameter.

If you really wanted to sort bullets though, the thing you should check initially is bullet base to ogive rather than bullet overall length. For that you'd need a bullet comparator.

I have the bullet comparator and have used it pretty good so I’m good there. Thinking of tools to use never ends

 

[Rommel Garcia]

Neck walls aren't always single thickness, which is another part of the problem. They can vary around the mouth and along the length.

In general, for this work you need micrometers not calipers, and you need anvil-shapes that work with concave+convex shapes, not just flat surfaces.so there's both some basic tools and basic techniques involved that are worth brushing up on.

its worth reading some of the 6mm br .com articles if this stuff is all new.

alternatively, this vid of UR doing a/b comps maybe is useful?

This is awesome. Thank you for sharing this!

 

[Rommel Garcia]

Neck walls aren't always single thickness, which is another part of the problem. They can vary around the mouth and along the length.

In general, for this work you need micrometers not calipers, and you need anvil-shapes that work with concave+convex shapes, not just flat surfaces.so there's both some basic tools and basic techniques involved that are worth brushing up on.

its worth reading some of the 6mm br .com articles if this stuff is all new.

alternatively, this vid of UR doing a/b comps maybe is useful?

What kind of Micrometer is that? Can’t seem to find it online.

 

[ma smith]

What kind of Micrometer is that? Can’t seem to find it online.

Spherical face (aka 'ball') micrometer.

UR's vid looks like trade dress of this one here (but haven't verfied the SKU)


For a general overview, possibly consider...

Mitutoyo

www.mitutoyo.com

 

[Rommel Garcia]

Yes, at one diameter of 4mm.
Would you at all mind posting pics of how you're positioning your caliper jaws while taking the measurements?