Ogive Diameter - Machining a bullet comparator tool.

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awesomealvin

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Hello fellow Reloaders. I've been wanting to machine my own Bullet Comparator Tool, anyone know what's a good source to find the Ogive diameter that I should machine to?

Only source I can find is this article on Sierra's blog -> https://sierrabulletsblog.com/2016/12/28/what-is-caliber-of-ogive/

Sounds to me like the ogive diameter is determined by the bullet geometry and not the caliber. If that's the case, is the Hornady Ogive tool just machined to a "ball park" number?

Thanks
 
Hornady ogive comparator diameters:

22 cal - 0.213"
26 cal - 0.2535"
30 cal - 0.299"


awesomealvin said:
Hello fellow Reloaders. I've been wanting to machine my own Bullet Comparator Tool, anyone know what's a good source to find the Ogive diameter that I should machine to?

Only source I can find is this article on Sierra's blog -> https://sierrabulletsblog.com/2016/12/28/what-is-caliber-of-ogive/

Sounds to me like the ogive diameter is determined by the bullet geometry and not the caliber. If that's the case, is the Hornady Ogive tool just machined to a "ball park" number?

Thanks
Click to expand...
 
If it's a comparator tool you wish to make, would it really matter what the diameter you choose to machine is? As long as the tool diameter falls somewhere "safe" on the ogive, your comparisons would be consistent (with consistent bullets of course).... Having the tool machined too large (very close to bullet diameter) or very small (approaching tip diameter) would not be desirable... However somewhere mid between these extremes, would seem ideal....
 
Irons78 said:
Hornady ogive comparator diameters:

22 cal - 0.213"
26 cal - 0.2535"
30 cal - 0.299"
Click to expand...

eschafer said:
If it's a comparator tool you wish to make, would it really matter what the diameter you choose to machine is? As long as the tool diameter falls somewhere "safe" on the ogive, your comparisons would be consistent (with consistent bullets of course).... Having the tool machined too large (very close to bullet diameter) or very small (approaching tip diameter) would not be desirable... However somewhere mid between these extremes, would seem ideal....
Click to expand...

Hmmm. That does makes sense. Sounds to me like if I machine a hole 0.008-0.010" smaller it's all good.

As a sidenote, does everyone already have the Hornady Tool? It's $70-$80 retail, am I the only one too cheap to buy one? I got an idea for a simpler design. If I get a bunch of these made, would anyone be interested in one? For say....$40 shipped?
 
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I made my own from 3/4 inch brass round stock. Hole diameter was determined using the diameter of the barrel lands from SAAMI chamber spec's. I'm cheap, and had a combination of idle time and access to a lathe.

So far I've made .243, 6.5mm, and .308

Simply machine the body to a convenient length, I used 1.000" for all of mine. Zero your caliper on the gauge when you start.

In my experience, bored holes can taper slightly from end to end of the cylinder. I'd suggest marking one end for reference and use that end for the bullet every time.

As long as you're within a couple thou of the "right" diameter, you'll be fine. You just need to remember that the numbers you get with your tool may differ slightly from someone else's using a different tool.
 
Chilly807 said:
I made my own from 3/4 inch brass round stock. Hole diameter was determined using the diameter of the barrel lands from SAAMI chamber spec's. I'm cheap, and had a combination of idle time and access to a lathe.

So far I've made .243, 6.5mm, and .308

Simply machine the body to a convenient length, I used 1.000" for all of mine. Zero your caliper on the gauge when you start.

In my experience, bored holes can taper slightly from end to end of the cylinder. I'd suggest marking one end for reference and use that end for the bullet every time.

As long as you're within a couple thou of the "right" diameter, you'll be fine. You just need to remember that the numbers you get with your tool may differ slightly from someone else's using a different tool.
Click to expand...

Gotcha. I got something a little more "unique" planned and solves the taper issue that you mentioned And yes it does makes sense that this is a "comparator" tool not a measurement tool. The depth of the chamfer around the hole can throw off the measurement.

Anyone interested if I get a bunch of these made? $40 each?
 
The Hornady package best met my needs and I have the 22, 24, 25, 26, 27, 28 and 30.

At $40 per unit one would only be able to afford two based on the current Hornady price but I don't begrudge the man with the equipment and talent.
 
horseman2 said:
The Hornady package best met my needs and I have the 22, 24, 25, 26, 27, 28 and 30.

At $40 per unit one would only be able to afford two based on the current Hornady price but I don't begrudge the man with the equipment and talent.
Click to expand...

My $40 design would include the 14 most common calibers.
 
Always interested in new stuff. At least willing to have a look.

With regard to your hole sizes, it really doesn't matter a heck of a lot, as the measurements you take are merely reference measurements. None of the tools we get give us a specific location on the ogive, or at least as far as I know. The main thing is getting a reference measurement to get a figure for where your rifling is and to repeat that dimension when loading.

The .01" or so smaller than bullet dia. seems to be a good suggestion. another .01" smaller wouldn't hurt one bit either.

Rooster
 
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