mrbb gave you good advise,and yes if your only hunting deer , even at extended ranges,
the 7mm mag with proper ammo, (generally 154-170 grain bullets) in that rifle will certainly be adequate
I know two people that own remington sendaro rifles , both are very accurate,
but I'd point out almost every deer or elk anyone, in the hunt club I belong too,
has shot in the last 5 decades, was killed at under 250 yards,
most of the guys I've spent decades hunting with, have tried the various 300 mag rifles at one time,
no one I know has ever found them wanting in lethality or accuracy, if they were loaded with a decent projectile,
and the rifle was properly bedded and sighted in.
that being stated, the 270 win, and 35 whelen both seem to be a more popular choice's with the older guys I hunt with.
If you have some spare cash, and want to enhance longer range accuracy, maybe upgraded optics would be an option,
example
https://www.midwayusa.com/product/62...-reticle-matte
if you want more power than a 7mm mag ,
a 300 mag is certainly a good choice,
but if your looking for more punch,
,Id suggest jumping past the 30 caliber to a 338-340 caliber rifle