New Tikka & 6.5CM headspace

[Tim_WNC]

TL/DR: Once fired brass measures 1.558" base to shoulder. OK?

So, I have a new toy and not sure I understand the numbers I'm getting.

Here's what I'm working with
1. Brand new Tikka T3x Tac A1, exactly 60 rounds down the tube.
2. Brass is from Hornady Match, factory load 1x fired from this new Tikka.
3. Brass is untouched since being fired - has spent primer, is not tumbled, etc.

My Hornady Headspace comparator tells me that my headspace is 1.558". That's measured consistently across 10 cases.

1. In looking at the SAAMI specs, this 1.558" seems long? Best I can find is that 1.551" is max.
2. Am I supposed to deprime and tumble before measuring?
3. If you were me, would you resize back to minimum spec or just bump back .003" and still be over spec?

I'm not new to reloading per se, just new to actually being precise about it. Previously I just set my el cheapo dies according to the manual and called it good.

 

[fxdrider]

My Hornady Headspace Comparator shows my Star-Line brass fired from my Tikka T3X CTR in 6.5 Creed as 1.562". I bump it back to 1.560" and call it good. Someone with more knowledge can better say if I'm wrong for doing so, but it's worked well so far.

 

[PinesAndProjectiles]

Your comparator and what was used to create SAAMI spec aren't the same. Most aren't.

Hell, you could use a 9mm case to measure headspace if you needed to.

I would bump the shoulders back .0015 or .002 inches regardless of what you're using to measure and call it a day.

 

[spife7980]

Take an actual headspace go gauge and measure it with your comparators and calipers. You’ll see that the reading does not match what is printed on the gauge.

Your case comparator is just that. Compares the fired dimension relative to the sized. It doesn’t give you absolute measurements, it gives you relative.

 

[Milo 2.5]

Yes, you should decap before running these measurements. But these guys are right, these are your numbers, go from there.