Re: Leupold M1 question
That is the frustration of the M1 turret, you have to know where the 100 yard zero is re the little lines you talked about. I find it much easier to take a razor edge and make a tiny scribe mark on the side of the turret facing left as you aim the rifle - then just crank down to it. You could also make the same deal with nailpolish, just any reference other than having to remember which of the Leupold lines to go to.
Some turrets zero close enough to the bottom that you can just crank to the bottom and up a bit. You would have to go all the way down and then up three revs. That is not very quick a refence tick or dot or whatever on the side of the turret is easier.