speyrjb

I take a fired case, trim it and re-size the neck about 1/4 of the way down.

Then I seat a bullet in the case just far enough so the bullet doesnt fall out of the case. I then chamber the dummy round into the rifle very slowly so the lans push the bullet down into the case. I remove the dummy and measure it. This tells me what the distance to the lans are for that particular bullet.

It works for me. Not as accurate as that Stony Point guage but all I'm looking for is a rough estimate anyways. My rounds are never loaded anywhere near that length. I've always been able to find an accurate load with significant clearance of the lans. I've had better luck working up shorter loads than longer ones in the guns I've loaded for. Just my experience tho.