I'm really new to this so this may be a dumb question. I've done my ladder test and came up with a 42gr load. I can load 4 or 5 rounds and have 3 or 4 shots in the same hole or really close. In every bunch there will be 1 or 2 that are an inch or maybe an inch and a half away from the group. I've been playing with seating depth and think I have it solved then that one dang flyer makes me want to start over. Any ideas where to start or what might be causing this.

Do you use a concentricity guage? I find that if the barrel is free bored,I like having less than .002 run out.

What are you using for a rest?

No to the concentricity gauge. I have a good sturdy table and a sled type rest.

How much time between each shot? If your barrel gets too hot, you can get those type of results. When trying to get a good group, I'll wait 5 minutes between each shot.

For me my hunting rifle .I set it for 1st shot cold bore. all after shots are to ck the change & where it changes. then I stop. it may take 2 days at same temp so all 1st cold shots match. for me its that 1st shot.last test 100 yds golf ball on a tee , clean hit.do this at hunting temp.

What the man said - First shot zero when gun is cold for hunting. Deer hunting isn't like target shooting at all. Take the worst light, bad angle, most unsteady position, and through the most undergrowth at an animal that won't hold still. That will be your hunting shot.

What it could be.
barrell heat up
are the brass fired in this rifle before?
could be a scope issue, Minimal possibility. But you have a minimal problem.
could be a flinch...Just sayin.
wind.
primer flash hole size or pluggage from case cleaner
type of bullet.
is it a mixture of military and other brass?
Question.
After the flyer does it settle back in the same hole cutting zero??
if this is the case.. and the flyer is enough to bother you while hunting, I recomend trying a different scope. at least eliminmate the problem,
Care to share your recipe?? Sounds interresting.

The scope is a vortex razor. Lapua brass. I think the problem was seating depth I have moved .002 closer to the lands and the problem disappeared. I'm loading 130 grain vlds over 35.5 grains of imr 4064. This is for a 260rem.