Where to mesure neck OD?


Well-Known Member
Jan 11, 2006
South Africa
My "precision loading", such as it is, came about as I started shooting new rifles. My 270 just kept going with the good old set of 80's RCBS dies and the only adjustment I made was to measure the shoulder bump.

Anyhow, I recently picked up a Lee Collet die for this as for my other calibers. Without getting into the whole thing on adjusting them, I did as I generally do and started measuring (everything!) to see the neck tension etc.

I broke out a few boxes of "new" mid 80's Federal brass. The first observation is how surprised I was at the consistent neck wall thickness. First 20; 19 cases under 1thou variance. I also noticed how nice and evenly the primer pocket uniformer cleaned up the bottom of the pocket. They are very square to begin with compared to most other new cases where the pockets are slightly "domed" I suppose, due to the punching of the flash hole.

Enough of that... whilst measuring the neck OD it occurred to me that this is the first caliber that I'm measuring that has a tapered neck! So my question is where you generally like to measure these to get a neck tension number? Sure, for my purposes as long as I'm consistent, I know where I stand on a relative basis i.e. more or less tension, but I'd like to know what the norm is. Of course getting the micro anvil flat is also a lot harder on a tapered neck anywhere other than right at the case mouth.

Any comments on how you do it and why will be interesting to see.


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