A 6-24x50 and a 3-15x42 are not the same at all. Vastly different capabilities, limitations, and suitable uses. Apples and oranges. What are you really wanting to do with the scope? Intended range of uses and primary use? I understand the AR10 and the 300 Win Mag bolt gun, but how would each be used?
6-24x50 scopes frequently have sunshades on the objective lens, which increases overall length. They are used to decrease glare, which is more pronounced at high power, and to mitigate mirage. Once the shade is added (which I highly recommend), the scope can actually interfere with the front sight on some shorter barreled AR's. I don't know the length of the barrel of your AR10 or whether it has secondary sights.
If you are familiar with such scopes, I apologize for raising the issue. I just wanted to make sure you were aware. I use such a scope for 5.56 load development and certain precision shooting on an AR15. It is superb in a limited role for which it is intended, but it dominates the rifle once mounted and certainly alters the weight and handling of the rifle. It was formerly on a Sako bolt gun chambered in 6mm Remington for varmint shooting. I'm looking for a replacement to put on the Sako. I use lower more mid-powered scopes for general use. Even on my Weatherby Mark V 300 Weatherby Magnum, my scope is only a 4-12x