headspace??

[wildchild]

Anyone have time and effert into finding a specific headspace that shoots better than another? With differances in how the bolt closes one can see groups go to shit in a hurry. Comparing a bolt closing hard to one that closes easy is two differant extremes so if one was to play with say .005 differances should on show up a on paper...not? By pulling the fireing pin out I could feel differances with minut amounts on changes in headspace, goes from a firm push to with .001 over to a bolt closing on its own with .002 under. This is crap I dream up and think about late in my man cave so any thoughts would be appreciated. Thanks
Also any thoughts with this on say 30 degree shoulder and one that is 40 degrees??? should it be a differant amount?

 

[BoydAllen]

In my experience if they all close with the same feel you are OK. If you alternate hard and easy in the same group, you are in trouble. In calibers that have heavier brass than a PPC it has helped to "heat stress relieve" cases to achieve more uniform bump. If you do not, the variance will either give you some that are bumped too far (if you do your setup with one of the harder cases) or the tight and loose problem ( if you use one of the softer cases to set the die). It seems to me that 30 degrees works pretty well, and I think that there is more potential accuracy to be gained by looking at things other than shoulder angle.

 

[wildchild]

As far the shoulder angle I ment the headspace clearance between the 2.

 

[fdshuster]

wildchild: To me, controlling headspace length has 2 advantages: With a firm bolt closing with just a little felt resistance, I know the ctg. is locked up tight in the chamber, front to rear. When the case is a snug fit in the chamber, the brass will not stretch during firing, resulting in case trimming rarely ever being called for, and even if it is trimmed, only a few thousandths is trimmed off. I have Lapua 220 Russian/6ppc and 6BR brass that have 35 to 40 reloads ( I keep count on # of reloads) and have yet to have a case head seperation or for that matter even the beginning of the seperation ring near the case head. I've always sized the cases to keep headspace the same dimension as fired. After about 4 or 5 loadings when I feel more resistance on bolt closing the shoulder is set back .002". Have I ever noticed a difference in Accuracy? No, but I never have differences of more than .002", not the .005" you mentioned.

 

[DCRYDER]

I think different amounts of pressure will cause the harmonics to go crazy. I always F/L, bump mine .001" to .0015". I never only neck size. Seems like when i used to neck size only the "tight" ones shot to the left.