home made bullet comparitor

[JimSC]

I saw the thread on bullet comparitors yesterday and decided to see if I could make my own and improve on the Hornady comparitor by making it into a bench tool. Here is waht I came up with in about an hour this morning. It works fine and certainly is faster than using the tool with the calipers.

I think I might be at or approaching the point in my shooting where getting down into the weeds a bit farther might be worthwhile and might start sorting bullets. Anyway it was a fun little Sunday morning project. The base is some scrap hard maple and the ends were cut from a old teflon cutting board. Total cost outlay was zero since all the wood, screws, etc were left over from old projects and the dial indicator and comparitor base and inserts were already on the bench.

 

[David Christian]

Looking good. I might cut away the 90 degree angles on the cutting board material so that your hands have more room around the bullet.

 

[savagedasher]

All that is needed is a drill and a file

 

[dolek]

Looks good,..simple design...all a person needs .

 

[nmkid]

Very nice. Simple, yet it should work just fine. Good work. Might just have to follow your idea!

 

[Puzzaz01]

I like it, nice job.

Darrin

 

[butchlambert]

What are you measuring? OAL?

 

[chromatica]

Noice! I like to customize my setup and take inspiration from others who do the same. Good job!

 

[JimSC]

What are you measuring? OAL?

bullet base to ogive

 

[Mikemci]

What are you measuring? OAL?

He's measuring ogive to bullet base.

 

[BULLET 05]

Great idea!!! Well done.

 

[AlNyhus]

bullet base to ogive

Jim, try this:
1. Select the two bullets whose base-to-ogive vary the most.
2. Size two cases, leave the primers out.
3. Seat a bullet in each case.
4. Using a dial caliper and your comparator, measure case head-to-ogive on both and compare.

Looking forward to your results. -Al

 

[JMayo]

That's interesting. But doesn't accomplish anything for me.
I'd like another hornady. #23 on the other side to measure bearing service ....

 

[dcali]

Sinclair/Brownells makes a nice version of this concept. Same thing, just a dial indicator on a small granite plate with a cylindrical gauge-thingy to hold the bullet. It's a very good way to measure base to ogive.

 

[JimSC]

Jim, try this:
1. Select the two bullets whose base-to-ogive vary the most.
2. Size two cases, leave the primers out.
3. Seat a bullet in each case.
4. Using a dial caliper and your comparator, measure case head-to-ogive on both and compare.

Looking forward to your results. -Al

thanks, I am looking forward to doing some casual experimentation with this also. At the moment though I am not happy with the functioning of the unit. I should have tested it more before posting. As the current design goes, don't bother with one. I cannot get repeatable results.

The Hornady base works fine with calipers as it was designed to do, however it is just awkward and slow to use because of juggling the bullet in one hand and operating the calipers with the other. The upside is the wide blade of the caliper "seats" the ogive of the bullet into the datum hole more evenly and firmly. Results taking readings with it are very repeatable.

Using the dial indicator the bullet tends to tilt slightly in the datum hole and of course readings can vary several thousandths. I discovered this after comparing the same 10 bullets using the calipers handheld and spinning the bullet to get a initial set of readings then measuring on the dial indicator setup and with and found that wiggling by the bullet in the dial indicator setup I could make it agree with the readings taken with calipers or be .003 or more off. Not very repeatable results I am afraid

I do have a couple of ideas on how to remedy that issue. I going to try making custom datums out of the cutting board plastic using a hot bullet and a arbor press or spinning the bullet in a drill press. Of course a separate one would be needed for each caliber and style bullet so the bullet that I use but they will be held firmly in place with no wiggle room. I also want to get a spare calipers and attaching them to some sort of base to make them more user friendly.

Sinclair/Brownells makes a nice version of this concept. Same thing, just a dial indicator on a small granite plate with a cylindrical gauge-thingy to hold the bullet. It's a very good way to measure base to ogive.

or I might just buy a set of the Sinclair inserts and use my own dial indicator and stand, thanks Damon. That looks like the best setup I have seen so far in one of these

 

[gunsandgunsmithing]

I've made a few for folks that use redding die bushings and a digital dial indicator. They do work well and very easily. I don't think I have any pics though. I'll have to look.

 

[6MMsteve]

I saw the thread on bullet comparitors yesterday and decided to see if I could make my own and improve on the Hornady comparitor by making it into a bench tool. Here is waht I came up with in about an hour this morning. It works fine and certainly is faster than using the tool with the calipers.

I think I might be at or approaching the point in my shooting where getting down into the weeds a bit farther might be worthwhile and might start sorting bullets. Anyway it was a fun little Sunday morning project. The base is some scrap hard maple and the ends were cut from a old teflon cutting board. Total cost outlay was zero since all the wood, screws, etc were left over from old projects and the dial indicator and comparitor base and inserts were already on the bench.

View attachment 1085246

that's my kinda style, same results and cheaper,

 

[olddav]

To the OP, exactly what I was thinking approximately two days ago. Good work and now I don't have to do any design work. I'll just copy your work.

 

[JimSC]

To the OP, exactly what I was thinking approximately two days ago. Good work and now I don't have to do any design work. I'll just copy your work.

if you do get these Sinclair inserts to use as datums https://www.sinclairintl.com/reload.../sinclair-bullet-sorting-stand-prod38769.aspx and then just use a regular dial indicator stand

the Hornady's little datums does not support the sides and lets the bullets wobble too much without using the calipers. Also you might want to get a flat tip for your dial indicator like this one https://www.mscdirect.com/product/details/35916121

Before I spend much more time or money I want to test it to see if I can see any on target benefits. I used my calipers with the Hornady tool tool to sort out 25 from a box and I want to check to see if they group and chrono better than unsorted.

 

[olddav]

A simple solution is to just stand it up on end. Not perfect but close enough for starters!