I too have killed deer and similar sized critters with a 300 winmag, and a 300 RUM. I just wanted to experiment,ha. later, I had a couple opportunites to shoot Plains game ( up to elk size) and I wanted to use my rifle before I went over.
My best load turned out to be the older Barnes 180 XBT, today the 180TSX is even better. However, on a Texas Hill Country deer hunt, I tried some regular Federal Blue Box 150gr in my 300WM, I thought I would get the 'bomb" effect. Turned out they acted like 180 Partitions, zipped through, lots of damage and even "syphoned" lung tissue out the 2" exit hole,ha! Surprised me, but these are small deer, 85#does to a 125# buck.
My worst bullet on game was the aforementioned "older" 180 ballistic tip (they are tougher now). It was very destructive on a little antelope doe (but a true 344 long steps out on the prairie!) and a medium muley buck at 75yrds. I went to the Barnes then.
There is no way we Americans, with our short seasons and opportunites will ever get much use out of "our elk/african rifles if we 'don't" use them on deer/coytoes/hogs. Sure, I would handload now if you haven't ever started, then you can make a dedicated whitetail round for it (300 savage to 30.06 level) if it kicks more than you like, a good muzzlebrake is an easy fix. I like muzzlebrakes because they help me keep my sight picture at the shot (usually) so I can call my shot/effectiveness at long range. But a good scope is always a good idea , and I always preferred Leupold. BUT, I gave a 300 RUM to a favorite uncle, no brake on it, and he wanted to use his favorite scope, a Simmons 44Mag, it is still holding up after 13 yrs! If you put a brake on it, the "airgunpistonlike" opposite force during recoil arrest will wreck most scopes. Good luck to you, and get that "magnum" ready for deer season!
I got my first 7mmRemMag in 1973, a BAR, to use on elk 'someday" and I used it on the little East Texas deer we hunted. I used the 175gr CorLokt factory loads, and it did not mess up any more deer than 30.06 did, but boy! did I ever catch flak from all the "experts" telling me "what do you need that for"? As If..it was any of their bizness! ha. Just smile and tell them you are prepared for Sasquatch! ha