Relationship between headspace and chasing the lands?

[JFrank]

The chamber has headspace, case has setback to cycle freely through the chamber
Just to put it into perspective .003 is slightly more than a human hair and hardly enough to cause overworking.

Just my experience.

 

[searcher]

Just offering my experience on this
being that brass is soft compared to the action
I had it in mind to set the shoulder back perfectly to the chamber
IE: you could feel slight resistance closing the bolt on a newly sized piece of brass
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There were times where occasionally one piece of brass would be harder to close the bolt on than others
I decided while providing good consistency in what you spoke of
maybe that wasn't so good for the bolt lugs in the long run.
I prefer now to be easily able to close the bolt when chambering a piece of brass
so set the shoulder back somewhere in the area of .001" - .002"
(if it is .002" on a newly set up sizing die... I may decide to fool with it later)
any more than that and I would say its more for ensuring a hunting gun can cycle ammo if dirty

To get that "perfect" slight resistance when the bolt is down around 75% on a round-to-round basis is not easy without some pretty meticulous brass prep. Inconsistently annealed brass alone will result in a slight variation in resistance when closing the bolt due to brass spring-back. I strive to get all that as good as I can on my target rounds. For varmint work, I'm happy with .001"-.002" off the shoulder - and my A/R's .002" to .003". That small amount of resistance on the target loads doesn't concern me in regard to bolt wear. I just keep that bolt clean by pulling the bolt and wiping it every so often and lightly grease the lugs. Maybe one way to view the difference in bolt resistance is using it as a gauge of sorts to let you know how consistent your ammo is. With no resistance, there is no feedback in that respect.

 

[searcher]

IMO an absolutely horrible way to attempt to solve a doughnut situation.

I agree - to knock the shoulders back only .001" surely isn't buying anyone much room to avoid a doughnut - and that would be a rarity that the actual bullet being used would be able to be manipulated successfully with that .001". I was really "stretching" it as to why someone might bump the shoulder more than needed - and as to what their logic or purpose was. My point was more "why would you do this?" One could conceivably push the shoulder back on certain bullets and avoid a doughnut, provided no more than .004 - .005" were involved. That, of course, would result in a lot of brass stretch, premature case life - and a host of other issues with flattened primers, expanded bases, possible case ruptures after several firings.... As you say - a VERY bad way to avoid a doughnut.