Comparator?

[PWC]

I have seen what looks like a large hex nut with holes in each of the flats. I believe, or at least I would like to use it to measure bullet seating.

Can someone tell me what it is, what it's called, so I can look for one?

Does such a thing xist for case shoulder measurement? Yes, I know about the Hornady tool, but I'm asking about a "hex nut".

 

[Varminterror]

Pacific Tool and Gauge (PTG) makes hex shaped bullet comparators.

http://pacifictoolandgauge.com/reloading-tools/946-bullet-comparator-22-24-25-26-28-30-calibers.html

 

[Walkalong]

I have seen someone here who took large hex nut and drilled it out for shoulder measurements. Drill it out the diameter of the datum for that caliber. A drill press to keep things square would be best.

 

[lightman]

The one that I have came from Sinclair.

 

[mrawesome22-250]

https://www.sinclairintl.com/reload...r-hex-style-bullet-comparators-prod83792.aspx

 

[AJC1]

I have seen someone here who took large hex nut and drilled it out for shoulder measurements. Drill it out the diameter of the datum for that caliber. A drill press to keep things square would be best.

Those holes are not just drilled they're reamed to a very close tolerance and even the chamfer that you put on the edge to take off the burr will give you slightly different measurements

 

[higgite]

Those holes are not just drilled they're reamed to a very close tolerance and even the chamfer that you put on the edge to take off the burr will give you slightly different measurements

I don’t believe a deburring chamfer will hinder its intended purpose. It’s a comparator, not a precision dimensioning device.

 

[Walkalong]

Those holes are not just drilled they're reamed to a very close tolerance and even the chamfer that you put on the edge to take off the burr will give you slightly different measurements

As long as the measurement is consistent all is well. I have the Sinclair one linked to above. A slight chamfer will actually make it easier to get consistent measurements vs a sharp edge.

Here is a home made one for .308. I just cut it at the .308 shoulder angle, works like a champ.

 

[mrawesome22-250]

As said, hole size doesn't matter a whole lot. You are comparing one number relative to another, not measuring.

 

[JFrank]

As long as the measurement is consistent all is well. I have the Sinclair one linked to above. A slight chamfer will actually make it easier to get consistent measurements vs a sharp edge.

Here is a home made one for .308. I just cut it at the .308 shoulder angle, works like a champ.

View attachment 886890 View attachment 886891

Home made Gizzy!
For Bullets I like a precise comparator , maybe I’ll try the pacific tool and gauge.

 

[Walkalong]

I like the Sinclair for bullets.




My old Sinclair comparator.

Home made Gizzy!
For Bullets I like a precise comparator , maybe I’ll try the pacific tool and gauge.

Notice the chamfer on the holes.

 

[243winxb]

Photos 223.

A 9mm case , mouth round and square will measure 243, 308, 3006 head to datum .

Take fired bottle neck case, measure, compare to fl sized.

 

[jmorris]

I have seen what looks like a large hex nut with holes in each of the flats. I believe, or at least I would like to use it to measure bullet seating.

Some like to make this confusing but the hex isn’t a nut just something with 6 different size holes in it.

https://www.brownells.com/reloading...r-hex-style-bullet-comparators-prod83792.aspx

The hole, any hole, of a given diameter, will contact an ogive of a bullet at the corresponding diameter, that is good for relative measurements.

You don’t need a hex, or anything else special. If you have a flat bar that you can drill a hole in and the tip won’t contact your measuring tool on the other side, you are good to go.

“Datum”, is the term used, and it is arbitrary, up to the point you designate it. A fancy way to say “a fixed starting point”, doesn’t matter what size it is, as long as it’s the same, for the particular measurement you are making. One for a .17 Remington will be a lot smaller than for the ET used on the Space shuttle’s.

If you were wanting to reference bullet seating on a .223 you wouldn’t want to use a .300 datum/hole because it would be useless, as wood a .187” diameter one for a .458 flat point.

 

[mrawesome22-250]

I use to make them out of pieces of square stainless. That was when I was young.

I now realize that all the comparators and run out guages and weighing cases and all that junk don't amount to a hill of beans when the nut behind the trigger has the most influence on fine accuracy.

 

[JFrank]

I like the Sinclair for bullets.
View attachment 886923

View attachment 886922


My old Sinclair comparator.
View attachment 886924

Notice the chamfer on the holes.
View attachment 886927

I have the Hornday, it’s just (OK) not great or exact