The ATip I’m my experience typically likes to be loaded long. But I have experience some very good groups 15 to 25 thousands off the lands. So if would try 2 thousands inside mag box first and bring it in closer in 2 thousands increments. You can usally see if it is going to group in 2 shots. If the first 2 are not close, the third one typically won’t be either. Look at your groups if you have a couple different loads with potential, shot a third shot, if not pull the bullet and save components.
I had talked to the Hornady rep and he said that the jacket is softer than the ELD jacket that is why you need the A tip seater, that being the case then they would like it closer, I will try about 30 loads ,like you said I don't waste bullets working up loads,2 shot per load ,IFFFF they don't work then will use my tuner and if that does not work will make some heavy FANCY Ear Rings,,,,,,,,,,,,,,,,,to sell, Pete
I would first be asking myself why i chose a 338 cartridge?
And my answer would probably be because of its potential for long range performance.
And that would mean that more velocity would probably be better than less velocity.
So i would load just one round and shoot it into say a dirt pile at 50’ over a chronagraph.
Then i would shoot one more round about a half grain heavier over the chronagraph.
Than another a half grain heavier, then another, untill he gun told me to stop.
Then i would back up a bit and load 3, and shoot those for group.
If i wasent happy with the group id change the seating depth, and change it again if necessary before moving on with a powder charge change.
As for the magazine, i never use one on my long range guns, but if i did, i would of coarse use that for my seating depth.
And i would be testing my groups at 400 yards, not 100.
Who cares how well a 338 shoots at 100 anyway?
Hey Montana, lived in Billings for around 25 years, really loved, Being a Masonry Contractor the winter could give yo fits but I made it ,did a lot of Coyote hunting in the winter when hides were in the $100.00 range, bought a lot of groceries tat that time. Pete