Barry Davies wrote:Why " bump " the shoulder at all?
Talking .308.
If your head space is set at say 1.630" then all fired cases won't come out at 1.630". There will be a variation of maybe a thou either side.
I set my body die to give an average of 1.630" ( my rifles are 1.630" ) in other words some shoulders are bumped a thou some are not touched.
Someone tell me what does it matter if some cases when chambered have a thou crush ( which you won't feel ) and some have a thou clearance?
Does it make a significant ( or any ) difference to grouping capabilities? I doubt it.
You will always get some variation because there are variations in every sizing such as -- more or less sizing lubricant, case hardness, slop in the press pivot pins etc. but as long as you are within a thou or so of rifle head space what does it matter?
Jase PTRC, Your measurements 0f 1.618 etc are not correct for a 308. 1.630/1.634 are Min/ Max so there seems to be something not correct with your gauge, I would fix that first.
Whether a tight case affects accuracy or not, I don't think it has MUCH effect. Maybe a better shot than me could tell the difference? Where I think a case with .001" crush will matter is gun handling if it is hard to close the bolt. I'm probably not the only one out there with a limited attention span and if I am struggling to close the bolt, my mind wonders away from what was happening down range. Maybe those who are lucky enough to have one of the lovely actions which Barry Davies makes won't feel much with tight cases but I know with the actions I use I can feel it and try to maintain some clearance. I would rather too much (.003") clearance than too little to make for easier bolt closing and less lug wear.