If base to shoulder datum measurements all check the same and this common length results in a truly zero headspace or reasonable, minimal shoulder setback on closing of the bolt then with nothing varying one shot to the next it ought not matter into where the bullets are going to impact. Best grease the working surfaces.
But, if base to shoulder datum is not exactly the same then neither is the amount of shoulder setback on closing of the bolt. The greater the shoulder setback the greater the shove the bolt has to put on the base of the case so the greater the stress, now also in varying amounts, that’s being dumped back into the action.
So, where stress levels were consistently minimal, or at least consistent, but now due to varying base to shoulder datum lengths it’ll take varying degrees of bolt shoving on the case to cram each of those varying lengths into the same amount of space so that now with varying stress levels being thrown back at the action, how is all this variance not going to affect where the bullets will impact?
Seems the choices are to either diligently maintain the brass so it’ll all always fit the chamber exactly the same, or if too lazy/not all that diligent then to me it’s a whole lot easier to bump back the shoulders to maintain a clearance of nearly none but still have some on up to ~ .002†between the bolt face and base of the case. The base to shoulder datum length can vary that same amount and still not stress the action on closing of the bolt.
But, if base to shoulder datum is not exactly the same then neither is the amount of shoulder setback on closing of the bolt. The greater the shoulder setback the greater the shove the bolt has to put on the base of the case so the greater the stress, now also in varying amounts, that’s being dumped back into the action.
So, where stress levels were consistently minimal, or at least consistent, but now due to varying base to shoulder datum lengths it’ll take varying degrees of bolt shoving on the case to cram each of those varying lengths into the same amount of space so that now with varying stress levels being thrown back at the action, how is all this variance not going to affect where the bullets will impact?
Seems the choices are to either diligently maintain the brass so it’ll all always fit the chamber exactly the same, or if too lazy/not all that diligent then to me it’s a whole lot easier to bump back the shoulders to maintain a clearance of nearly none but still have some on up to ~ .002†between the bolt face and base of the case. The base to shoulder datum length can vary that same amount and still not stress the action on closing of the bolt.