Re: Oal guage????
I bought several of those Max OAL measuring devices. Have returned to the use of a rod, as Mike describes. It's easy to do alone IF you have a gun cleaning vise to secure the rifle in.
Hardwood dowel rods in the right diameter are better than a cleaning rod, IMHO. I have one for each bore size I need, sanded smoooth and given a couple of coats of polyurethane to seal the wood against oil and make it easy to wipe clean.
It's impossible, in a strict sense, to mark (with a knife blade) the rod precisely and then to read it precisely, I mean withing a thousant or two, but that's really not neccessary for what we need to do.
Few factory sporter rifles shoot their best ON the lands, most shoot best from .025" to as much as .125" off the lands.
There is, usually, a range of seating maybe .015" wide that the gun won't see any difference in. I find and seat in the middle of that range and never worry about a few thousants of "error" one way or the other. I suspect that seating on the ragged edge of that range is at least a part of what causes flyers.