Thread: SAAMI specs Hornady Headspace gauge and Lyman Caliper

Hi Everyone

This is my first post. Recently discovered this forum - it's awesome!

I have been reloading for a little while now but have always kept it pretty basic. But then I went and got a headspace gauge and a bullet comparator from Hornady and I've been measuring stuff...

My fired 6.5 x55 Norma cases have 1.768" head space. Unless I'm reading it wrong, this would leave them well outside the margin of error for SAAMI spec of 1.786" . It would also, I assume, put the chamber of my Tikka T3 well outside min SAAMI chamber head space of 1.7834. (ie inferred from the size of the fired case, I assume my chamber is just a tiny bit bigger than that.)

On the other hand, a brand new Norma unfired case measures 1.765" (ie headspace measurement) which sits nicely with my fired cases and presumed chamber headspace, but again doesn't square at all with SAAMI specs.

The SAAMI measurements are off their webpage. All the other measurements are off my Lyman mid range digital calipers. So if they are consistently under-measuring by around .02" I guess that would make sense, otherwise... ????? wtf.