I had an incident a year or so ago when a guy shooting the same rifle that I have ( Remington 700P, .308 ), was just having a terrible time getting his rifle to shoot.
He asked me about my load and at the time I was shooting either 168 gr. Noslers or 175 gr SMK. My rifle was shooting pretty good so I gave him five or so of my loads.
He was unable to get a good zero with his factory load going all over the place.
I asked him to shoot all five and see where they went. He got a decent group.
I tried five of his factory rounds and my rifle threw them all over. At least a 4 inch group at 100 yards.
I decided to work up a handload with 150 gr. bullets and just had to give it up. My rifle won't group them worth a hoot. Makes little difference whether I push them fast or slow. It is just a no go for me.
I just stay away from the 150 gr bullets unless I am loading for the M1A.