Quote Originally Posted by gotcha
Had a HS problem w/ a barrel swap recently. Used a go-gauge & found fired cases matched the go-gauge H/S. But, W/ die set to S/H + 1/4 turn, F/L sized cases were .0015" longer & difficult to chamber. Chkd my shell holder & found it measured .246".... I could shorten the S/H or cut about .003" off bottom of die to get the amount of sizing flexibilty I needed. I decided to order three more S/H's from different Mfg's. here's what I got: S/H (A) .223", (B) .250" (C) .261" That's .038" difference in S/H's. ( industry standard is .250") If I didn't have a comparator & simply set my F/L die to the (A) S/H would the case have gone KABOOM from the massively short H/S? Maybe---maybe not. Without a doubt results could be head separation after a few firings or cratered primers or both, even if powder chgs had been worked up slowly. I really don't think setting HD SP w/ a F/L sized case is the best idea. If the above happened to me, it could happen to anyone. Rare circumstance? YEP! Could this happen to a novice BBL swapper w/ no go-gauge or comparator?.......................................
There's something wrong here. The notion that shell holder makers allow the important dimension to vary .038" is just not believable. GOTCHA, you're measuring the wrong dimension. The dimension that matters on a shell holder is from the top of the shell holder to the surface where the bottom of the case rests. The top of the shell holder is where the die stops, and the point where shoulder-headspace is measured from. I just measured 13 misc. shell holders and got .125" for each, as near as I can tell with the depth measurement part of a dial caliper. Thus, shoulder-headspace dies are made so that the headspace dimension OF THE DIE is .125" less than the nominal headspace dimension. Imagine a headspace dimension of 2.000". The die is made at 1.875". This plus the shell holder .125" = 2.000".
I set the die so that it is a solid stop on the top of the shell holder-no over-center snap thing is going on. The shell holder goes up and hits a dead stop.
Back to the lead-filled case as headspace gauge. The lead will and does keep the case from springing or feeling mushy. And, from changing headspace dimension. That's my point. If HS gauges are what you want to use, go right ahead. BUT, if you're a fired-f.l.sized-case HS setter maybe you'll like to try a lead filled case.
joe b.