Question on Sako barrel to bolt clearance

[akajun]

I have a sako aIII in 7mag from the 70’s/80’s I’m rebarreling. I measured the factory barrel tenon it’s .659 long measuring the receiver/ bolt
I have .695 receiver face to bolt nose/ extractor
I always like .005 bolt face to barrel tennon clearance and find most factory barrels close to that. This factory barrel has about .039 clearance
Also the rear of the tenon is turned down to minor thread diameter about .085 long. The reciever is threaded past the bolt nose so it’s not for that.
Is this extra clearance and turned down area for safety or gas relief in case of a case ? Can I just do like I normally do on Remingtons, Mausers, etc and thread to the end and .005 clearance?

 

[gunsandgunsmithing]

As long as you have extractor clearance, I don't see why not. I like them set up pretty tight too...less unsupported case.

 

[swd]

What Mike said^^. I set everything up .005”-.010” usually that’s from the bolt nose but sometimes from the front of the extractor, whichever is closest to the barrel. And sometimes you can reshape the extractor nose slightly to close that distance.

 

[Dusty Stevens]

Put .010 to .015 on them hunting guns

 

[akajun]

Little update on this project . I threaded a dummy tenon today at .683 and blued it up. The bolt cycled fine ,But!!!!! If you pulled the trigger and re cocked the action the extractor would rub. Measuring the tip of the extractor showed it to be .680 when uncocked
I cut my dummy tenon to .670 and no more rubbing
Only .010 more case support than the factory barrel but no giant thread relief or “teat” at the end of the tenon either that I see no purpose for