I keep going back and forth on this. I talked to my gunsmith again and he agreed that past 800 yards on elk the 300 would be better, he uses a 338 edge for distance elk. We discussed further and he likes a 243 variant and his edge, so different guns for different purposes. I explained that I will not have the ability ($$$) to have multiple semi custom guns and he said for a one gun longrange hunter the 300 RUM and the 210vlds are about as good as it gets.
I think however I'm sticking with the 7 rem mag for now and here is why... Cost! I discovered that I can use my rem mag action to rechamber but there will be additional cost in addition to the blueprinting, feed ramps and things like that. Also in order to run them ( the RUM) I will need to get a wyatts Box magazine or seekins dbm and this adds another 250. In addition to that I will have to install a muzzle break (would go with a DE) adding another 180$. On top of that I would need new dies 209$ for the redding competition die set which I already have for the 7 rem mag. Then there's the cost of powder and bullets, not a big difference but a factor. The farthest I have shot to date is 412 yards on a menacing rock, so I have lots of shooting to do before I go out past 800 on game I believe. So this is already building on a budget and the extra 500$ , 680 if you count the muzzlebreak, just doesn't seem feasible right now. My plan is to shoot often and save up and maybe get deals on the components I need by keeping my eyes open. Hopefully in a couple or few years I will burn the barrel up and have the funds and skills to justify the 300 ultra. In case you are wondering why not the 7 stw cost of dies and the smith said I'll use up that barrel much faster than a 7 RM. So I'll use this rem mag as a progressive step both cost wise (blueprinting action and getting a true 1/2 MOA
and skill wise (less recoil and arguably a better round to "learn" with). But then tomorrows another day and I love changing my mind, just ask my girlfriend...... ohhh wait I broke up with her ;)