[Unclenick]

Bart,

It has to be somewhere in that ballpark just because the malleability of brass doesn't let it stretch too far before it yields. Did you get to try this at different load pressures to see how much difference that makes? Full pressure neck sized-only cases will gradually grow too snug to chamber when they've been through enough load cycles, requiring a cycle with full length resizing before they can start to be loaded by neck sizing-only again. But if the loads are on the lighter side, they seem to go on forever (well, until the neck splits, if you don't anneal them).

That suggests a pressure sign. If you know what size brass is coming out of your chamber at normal pressures, if it starts coming out longer, the steel must be stretching. I know M.L. McPherson uses case growth as a pressure sign in Marlin 1895's, but there the locking lug is so far behind the boltface and the length of receiver walls being stretched is longer than in a front lug bolt gun, so I just assumed it wouldn't work in the latter. But maybe dragging a Precision Mic or similar tool to the range to monitor growth from head to shoulder datum in bottleneck cases during load workup isn't a bad idea for a second opinion.