I use a comparator on a dial caliper. Ain't perfect but its a shot. I have a nylon insert cut from years ago by a guy that isn't with us anymore that gives me a good idea if anything changed.
Shorter leads just lessen the chance you have to shoot with jump to the lands. IF you have any jump you have a chance at less accuracy, it can wobble some before engaging rifling and have a chance at engaging crooked so to speak.
I generally have tight throats since I have freebore in chambers due to some rapid fire issues in my ARs, but if its snug, it can't wobble as easy. I generally have my long range stuff to where I'm either 10th off the rifling or 10th or more engaged, almost soft seated. I deal with that.
What gets folks in trouble with short leades is that ammo is loaded to pressure assuming it'll get a running start at the rifling... and if it does not, if it gets jammed, it can over pressure.
I have a 75 amax deal... I load long single shot rounds and used to load some to mag length. you do NOT even come close to using the same load.
A tight throat will only get you in a bind if you have a fat bullet so to speak.... other than that a tight throat is a good deal, but you didn't want it for "combat" use either.
So the last answer to your last question is yes, you have that right. And before that yes, a short lead can help accuracy.
