I've had 3; .243, 7-08, .300 WSM
. The 243 and 300 both made pretty consistent 3/4 MOA rifles. I shot a lot of marmots with the 243, the longest ones between 450 and 562 yards. It and the 300 were really nice rifles for the money.
I could never get the 7-08 to do better than 1.5 MOA. That would still be fine as a 400 yard deer rifle, but it did not stay around long enough to get tested at that range.
A Montana, or any rifle that light, at 1500 yards is someone's dream... they just haven't woke up yet.
If yours shoots well, and if you can shoot a lightweight well, it will make a 600 yard rifle.