Sinclair Hex Nut

[amce]

G'day All,

Was looking at some .308 Winnies today. Rechecking them against my load catalogue. According to my notes these should measure 2.208" (Sierra GK SBT 165gr) to the ogive but I was getting 2.218". After a while I remembered that I have two Sinclair hex nuts. Both have a .30 calibre hole. Using the other one I was back at 2.208". This was the nut I used when I made up the rounds.

Would've thought that the two would be closer to each other than 0.010" or am I just too anal?


Cheers

 

[Mikecr]

You should let go of one too many.
Also, be sure to zero on the nut before taking readings.

It's way unlikely 10thou diff in hole diameters. Truly, it takes nearly nothing on a bullet ogive to cause 10thou shift in datum. With this, comparator tools will vary, and so you should pick one and always use that one.

I don't know when they come out with the nut, but I must have nearly the first and been using it ever since. It just works really well.

 

[Greyfox]

I would expect it to be closer. Only have used one for several years but will keep this in mind. The way I use the one I have the absolute ogive measurement isn't as important as establishing the relative consistency of the measurement of my loads and components. I have seen ogive measurement variations with Sierras and Bergers vary as much as a few thousandths between lots. Bullet length can definitely vary as much as .010" or more while the ogive measurement from the base of the different lots is within .001-002". I understand the manufacturers ability to control the ogive measurement is much easier then the total length/ tip formation.

 

[amce]

You should let go of one too many.
Also, be sure to zero on the nut before taking readings.

It's way unlikely 10thou diff in hole diameters. Truly, it takes nearly nothing on a bullet ogive to cause 10thou shift in datum. With this, comparator tools will vary, and so you should pick one and always use that one.

I don't know when they come out with the nut, but I must have nearly the first and been using it ever since. It just works really well.

Yep, stupid with two but the first one was purchased before I got a .260 Rem and it doesn't have the .26 hole. Had to get a second one for that. I have only used the one and same nut for the .308s and it was only today that I noticed the difference. I now keep the first nut in my little box of thingys for the .223 and the other one in the box for the .260 and the .308

And yes, I always zero my calipers on the nut.

Cheers

 

[Mikecr]

You got it