Gunsmithing Tikka Bolt to Breech Clearance

[dustingaunder]

What do you all use for bolt to breech clearance on T3s? I did a mock up of aluminum and left about 10 thou but I can see the extractor is rubbing on it with no round under it. It’s below flush with a round but proud with no round. I think it’s right around 10 thou proud but do you add more clearance or live with it touching?

 

[dustingaunder]

Anyone? I’ve read people just live with it touching empty to people going .020 clearance. Is 20 too much?

 

[FisherT&C]

I took a Remington 700 sporter barrel and retro fit it for my T3. I turned down the recess to make it a flat breech and then turned down the threads to 1 inch diameter and rethreaded it. When I did that I never touched the original chamber and I think I had at least .020 clearance, maybe closer to .030, I've shot the shit out of it and never had any issues.

 

[dustingaunder]

I took a new Tikka apart. Measured with my Starrett depth micrometer.

Breech face to shoulder - 0.986”
Action face to bolt nose - 1.007”
Action face to extractor - 0.996”
Action face to bolt face - 1.1245"

Breech to bolt clearance of 0.021” from Tikka.
Extractor protrudes 0.011” and clears the breech face by 0.010”.