EDIT: The reason I am working up heavier bullets is I drew and elk tag this year instead of deer…
I bought a 300 win mag last year christensen mesa… nice gun… it loves 150 grain bullets…like the same hole at 100 yards…but with factory ammo I get all over the place with anything larger…so I am in the process of working up some 180’s 190’s and 200ish grain bullets…the question is this… If this gun won’t adjust to the heavier weights… how much trouble would the 150 grain bullet put me in…and does anyone have any ideas how to get this thing to shoot better with heavier bullets…Its frustrating…but I mean it is accurate accurate with the 150 grainer… but it will go from cloverleaves on the target to a grapefruit size patter at 100 yards whn you switch…and yes that is with a cold barrel…
If all your gun shoots is the 150gr, then that is what you should work with. It is all about shot placement, and a quality bullet. I’ve seen guys with 7 REM Mags with 150 gr bullets kill plenty of elk out here in Colorado. Speed kills! Just make sure you have a quality bullet that isn’t going to fail you.
Good luck if you do decide to try to find a load with a heavier bullet. I have a 300 Win Mag and hunt elk here in western Colorado with both 168 gr. and 180 gr. Nosler Accubond bullets. Never lost an animal, with my average shot being 350 yards, and longest being 630 yards all hand loads. Good hunting!
Look at some of the Barnes if you can get the 150 ttsx to shoot well that would be an adequate elk load.
Keep in mind the 150 grain copper monolithics are longer than the same wieght cup and core so you may be in the same boat but if it works? Otherwise i likw the above suggestion of the 168 accubond.