Just like the OP, I have been experiencing the exact same problem with my Super Grade in 338 Win Mag!
All over the target, sometimes making horizontal strings across the target with very little elevation variance, then it will throw one 3-4 inches high, all at 100yds.
Sent 4 rds downrange at the 150yd target and made a 4 inch round-ish group... That was the closest thing to a group I have had. The last day I spent at the range it was cold so I had plenty of padding due to the extra layers of clothing... Recoil fatigue was not an issue, I could have fired it all day.
I literally waited 5 minutes or more between shots when firing to allow the barrel to cool as thoroughly as possible.
I am handloading, setting up my sizing die to only size enough to allow slight drag when locking down the bolt when chambering an empty case. Also, I determined my max COL and tried a batch loaded to Hodgdons COL spec, then tried a batch set to a COL that facilitated .025" jump between the ogive and lands. I did find that things did improve somewhat with heavier powder charges although little discernible difference between the 2 differing COL's...
My rounds consisted of 225gr Hornady SST pushed by 71.5gr IMR 4350. (Hodgdon lists max of 72gr of 4350, I did work up incrementally, no over pressure signs at all).
I bought this rifle brand new last november, and got it close enough to hunt with using the only box of factory ammo I could find as I was not set up to handload for 338. I am now setup up to handload.
It's been very frustrating, I have taken steps to tune my ammo to my rifle chamber and have seen very little if any improvement. Yes, it is shooting "minute of deer" but I think I am reasonable to expect 1.5" or smaller groups at 100yds. From what I see, this should be childsplay for this rifle/cartridge combo. My cheap little Remmy 700 ADL Synthetic chambered in 270 with a short 22" bbl and cheap Read-Head scope will group 1" at 100yds with regularity so long as I am on my game. Yes, I know I pulled a shot or 2, but 75% or more of my shots I am confident I executed the trigger squeeze properly. Most times with the rifle would discharge before I expected it to, as I gradually squeezed and was nice and steady on the bull.
Different powder?? Different bullet??? Longer COL for less bullet jump to the lands??? I was thinking I would swap the scope from my 270 on to the 338, but after reading this thread, I am not sure if I need to. The scope is a Pentax Lightseeker 3x9x40. Bases and rings are Leupold.
I was also thinking that it is me?? In fact, I was leaning more toward it being a flaw in my shooting technique than anything... Which hasn't made total sense to me as I am not green to shooting and I am able to shoot quite well with the 270. Believe it or not, the 270 doesn't FEEL as though it recoils that much less than the 338, I attribute that to the 270 being on a significantly smaller and lighter platform.
I am out of ideas myself other than to get different powders and bullets to try... And then keep edging the COL longer and longer hoping for the results I am looking for...
Any help and advice would be greatly appreciated on this!
