Reloading hexagon nut for bullet diameter?

[xjda68]

I am not sure what this is for. It came with some reloading stuff I bid on and won. The numbers on top for each hole does not represent the hole diameter perfectly. All the holes are about 0.002" under.
This is the second one of these I have run across over time. Does anyone know what this is?

Joe

300914
300915
300916

[shooter bob]

For measuring base to ojive with calipers look on midway USA I believe they carry them

[G W Wade]

Sinclair sells a peoduct like this. It's a bullet comparator. You place the nut over your bullet and it shows where bullet ogive reachs bullet diameter. Handy for loading different shapes of bullets to the same jump to the throat. Once you determine the proper jump, you can set any shape bullet to the same point. Use calipher to measure from base to the other edge of the nut. Hope this makes sense. I am a reloader, not editor , GW Or typist LOL

[BK7saum]

https://www.brownells.com/reloading/measuring-tools/bullet-comparators/sinclair-hex-style-bullet-comparators-prod83792.aspx#:~:text=The%20holes%20in%20the%20Si nclair,bullet%20to%20the%20case%20head.

[xjda68]

Thanks, everyone! I just knew I had seen this item in the past

[lotech]

Sinclair Nut- I've used one for thirty or forty years. I can't recall trying it with cast bullets, but it should work fine. I've found it very convenient and far more accurate and consistent than other methods of measurement of overall length for jacketed rifle bullets.

[M-Tecs]

Sinclair Nut- I've used one for thirty or forty years. I can't recall trying it with cast bullets, but it should work fine. I've found it very convenient and far more accurate and consistent than other methods of measurement of overall length for jacketed rifle bullets.

It doesn't measure overall length. It measures the ogive length of bullets or loaded rounds.

[garandsrus]

You can use it with loaded rounds also. It tells you the distance from the base of the case to the ogive . This distance is used to set the bullet distance from the lands, or “bullet jump”.


I also use it to measure the shoulder setback when resizing cases if one of the holes contact the case shoulder. The numbers are caliber markings.

[lotech]

It doesn't measure overall length. It measures the ogive length of bullets or loaded rounds.

You're right. I guess I didn't think about what I had typed. I've only used it with loaded cartridges. I might add that you can quickly tell when a bullet has been re-designed or a new bullet die has been used by the manufacturer, one that differs from the old die. Hard to impossible to do this with many bullets by only measuring overall cartridge length.