Headspace Fussiness

[scaxeman]

Good day all,

Love this site! Lots of good info. My name is Darrell, I am an F-Class shooter, not a benchrest type, so forgive any unintended blunders. While I am not a benchrest shooter, I am passionate about my reloading,although still rather new to it). The question for the day is headspace. How exact do the headspace measurements have to be from one case to the next. Over most of my 2-3x fired brass, the headspace as measured by a RCBS "precision mic" varies by ~.0005". On one batch, that number varies by .002",+/- a little under a thousandth). Is this enough to worry about? Pretty much all of my brass is at the minimum end of the "go/no-go" headspace case gauge. Most of my competitions go back to 1000 yds, so it is important that this ammo stays under a minute at those ranges,especially with the new F-class targets).

Any help/info/perspective would be greatly appreciated.

Thanks

Darrell

 

[Clarence]

If the headspace of the Chamber is good to go, I would not worry about the case dimentions except to say when Fireformed you should not push the shoulder back more than about .001 or 2 max. If one pushed further, one stretches the cases at the Base area on the sucessive firings. In answer to your "F" Quest and knowing the competition factor one should do anything/everything one can do to produce Clones of Ammo.
I shoot the Palma Game and,being called paranoid)I allow no more than 1/2gr case difference in the box lot,60 rounds)I turn necks, I measure base to ogive, I qualify the primer pockets and last but not least use Russian Primers.
Try to keep the Headspace within .001 for all cases, this may be influenced by case Lube not enough and ya get longer case headspace too much and on the shoulder area ya will get the shoulder pushed back farther.

Clarence

 

[Aussie_bob]

And if you load into the lands does it really matter, also you say you only allow less than 1/2gr weight difference in cases where is the difference in the base or where? The only sure way to know you have consistent case capacity is to fill each case with water and weigh the capacity of each case to be exact.