Why can't i reload exact cartridges?

[XSIVSPD]

Yes^^^^

The Mic I use for measuring bullets cost $250.

For what he's after, even something. Like this from Amazon would be a huge amount better than the calipers and would give him a good accurate way of also checking bullet consistency, case head expansion etc. For what he's doing the calibration doesn't matter just the consistency so he can compare numbers.

After working in an aerospace machine shop I gained a lot of good tools for reloading. Micrometers are indispensable for consistent, accurate, repeatable measurements.


Anytime Tools Premium Outside Micrometer Set 0-4"/0.0001" Precision Machinist Tool w/Carbide Tips https://www.amazon.com/dp/B0045UZGSC/?tag=lrhmag19-20

 

[RockyMtnMT]

For what he's after, even something. Like this from Amazon would be a huge amount better than the calipers and would give him a good accurate way of also checking bullet consistency, case head expansion etc. For what he's doing the calibration doesn't matter just the consistency so he can compare numbers.

After working in an aerospace machine shop I gained a lot of good tools for reloading. Micrometers are indispensable for consistent, accurate, repeatable measurements.


Anytime Tools Premium Outside Micrometer Set 0-4"/0.0001" Precision Machinist Tool w/Carbide Tips https://www.amazon.com/dp/B0045UZGSC/?tag=lrhmag19-20

I think it runs into the point of diminishing returns. A well put together rifle will take care of everything.

 

[NEMTHunter]

Another good thing about a micrometer is if you get a blade one then you can also measure case head expansion with accuracy.

 

[XSIVSPD]

Here's just the 3-4" one for $35

Anytime Tools Outside Micrometer Professional Grade Precision Machinist Tool (3-4"/0.0001") https://www.amazon.com/dp/B01548KD5O/?tag=lrhmag19-20

 

[bigngreen]

I don't think I've seen it mentioned but how you run your press when seating will also make some difference, I always seat in a smooth motion and hold a couple seconds at the bottom with the same force and it'll tighten things up.

 

[Mikecr]

Can anyone show a jig for micrometer measure of CBTO?
I've used calipers and indicators, but not a mic for this.

 

[BallisticsGuy]

Maybe you just need the right dies.

http://exactshooting.com/

Yes, it was a pun. Yes it was a good one. Yes, it's also a possibly helpful answer to OP's question.

 

[XSIVSPD]

Can anyone show a jig for micrometer measure of CBTO?
I've used calipers and indicators, but not a mic for this.

Take the part of your comparitor that clamps to you calipers to a machine shop. Have them find the center, then mill a slot from center to the outside that your micrometer stem will fit into at the same depth as the current caliper groove with a flat bottom end mill. It should take them less than 30 min including the setup so cost wouldn't be too high. Just make sure they know it needs to be pretty parallel to the bottom where the insert sits.

If you explain to them what you are after and bring your mic for them to measure they should understand pretty quickly.

Edit: if they mill from the center instead of the entire length/width (like the caliper slot is) it will give you a good easily repeatable way to make sure your mic is sitting squarely on the comparitor. Otherwise you'll get inconsistencies until you develop a feel for getting it square/flat. And you want a slot instead of a pocket so you don't have to spend so much time spinning the thimble on the caliper ;-)

 

[Barrelnut]

As others have said it has to do with slight differences in neck tensions, bullet bearing surfaces etc. Keeping your brass annealed and bullets sorted (especially ones not held to tight tolerances) helps. Then just back the micrometer on the seating die back about .005 or so for each bullet and walk the bullet to the dept you want by seating, measuring, seating .001, measuring again, etc.
Your caliper is plenty accurate enough for the measurements. Just need to get a feel for it and use consistent pressure when measuring and learn to settle the bullet in the comparator.
It's the quickest and cheapest route to getting to where you want.

 

[Mikecr]

Take the part of your comparitor that clamps to you calipers to a machine shop. Have them find the center, then mill a slot from center to the outside that your micrometer stem will fit into at the same depth as the current caliper groove with a flat bottom end mill.

That could cover spindle side. What do you do for anvil side?

 

[XSIVSPD]

That could cover spindle side. What do you do for anvil side?

If your primers don't protrude use it as is Or have the machine shop pocket a spare shell holder to fit the anvil.

 

[XSIVSPD]

What would a cnc machined steel and ceracoated setup that uses standard comparator inserts and included an anvil cover/shell holder for most popular calibers be worth to you guys?
I have access to all the equipment to make it, and small flat rate boxes are pretty cheap to ship, even from up here in ak

For that matter what about a hard plastic version? I have a 3d printer that's accurate to 0.002" and leaves a good finish

 

[sedancowboy]

I find that if I bevel the inside corner of the comparitor with a VLD deburing tool that it makes them a lot more consistant. They are aluminum and so won't hurt your carbide tool.

 

[Mikecr]

It doesn't sound like a micrometer setup for this has actually been developed.
There are already indicated setups(on stands) which, as with calipers, can be as accurate as willing to spend for. Both would have the advantage of speed/ease of use over a micrometer setup.