"Zero headspace"? You talkin' to ME? Lets not get personal, now.

I was not kidding. And not being personal, just happened to be close to your screenname. Did you read my discription of the Encore posted above.-Rob

Oh, all right. Just trying to solve the mystery of my 45-100 on a Merkel 12 ga action stretching cases past loads that generate 35K psi. Suspect that the Greener bolt has slop in it, letting the frame spring a bit while the case walls are gripping the chamber. Definitely has zero headspace--a bur on the rim(or a .002" shim) will not let the action lock closed.

the 405 its cool it works when you shoot things with it they fall down boom!!!

XS Headspace- I suspect your Merkel diagnosis is correct. Did you ever try the primed case experiment. Just prime a case, fire it in the Merkel and measure the primer protrusion. I've seen guns with supposedly zero headspace move the primer out 0.01. Could be a worn greener crossbolt or worn action pin or barrel hooks. BTW on the Encore I have a oversize action pin that also helps to truly acheive zero headspace. My primers dont move on firing as described above.-Rob