I live in west Texas, in the high Chihuahuan desert where sneaking up on a game animal is very seldom an option. - Most shots are at longer ranges, and at tougher animals. - Mule deer and elk instead of white-tails, at 200-300 yards instead of 30-100 yards.
Hunting involves carrying your rifle around for extended periods of time over rough, difficult terrain. ( Mountains, rocks, cactus, etc. )
So, I am faced with the same problem as the original post lays out:
What's a good deer rifle for up to 300 yards?
For me, it's going to have to be easy to carry, which rules out the heavy tactical-style sniper rifles etc..
On the other hand, it will have to be both reasonably light - and yet still powerful enough for long shots without beating me up too bad. - I'm an OF with bony shoulders.
Accuracy is always important, but it is absolutely vital for long-range shooting.
Custom-tailored handloads can give you good accuracy with most rifles in good condition - but things don't always go as planned on a hunt - and the ability to get by with whatever ammo is available is important for that reason.
With the above in mind, my choice is a Browning A-Bolt "Stainless Stalker" in either 270 or 30-06 with the BOSS-CR barrel tuner.
I have owned a Browning A-bolt "Stainless Stalker" in the past, in 300 Win. mag caliber and was favorably impressed with the general handling qualities, accuracy and so on.
I intend to buy the "Stainless Stalker" model instead of the beautiful Medallion model - because the stalker is less likely to get boogered-up on a rough climb or trail.
I do not feel that a magnum is really necessary for the hunting here, thus the choice of either the .270 or 30-06 models which are a bit lighter to carry, and will kick less.
The BOSS-CR tuner is the the one that does not act as a muzzle-brake. Muzzle brakes are good at reducing recoil, but they are also loud and will PO a hunting guide. - For best results, do not PO your hunting guide on a $2-3k hunt.
I'll probably buy the muzzle-brake component too, but only use it for practice. When I go hunting or if the shooting range is crowded, I'll use the CR component instead.
What the tuner does for you, with or without the muzzle-brake, is allow you to get dime-sized groups with the ammo on hand.
So - you can buy factory ammo, tune the barrel with four or five shots while adjusting the BOSS, and you are ready for deer hunting up to 300 yards.
This is much easier, faster and cheaper than developing a custom hand-load. - But it works for hand loads too for the ultimate in inexpensive shooting. Just handload for velocity and let the BOSS tuner handle the accuracy end of things.
About the scope: The fellows who recommend a 4-12 instead of a 3-9 are correct. - You need more magnification at greater ranges.
My choice is the Nikon Monarch3 4-16x42 side-focus BDC.
I have this scope on a heavy-barreled 243 and have found it is be just as good or perhaps better than the Leupolds that I usually buy. Nikon has some free software which will match the BDC ovals to your load, so that you know exactly which BDC oval to use at what range. - That, and the good quality of the optics here make long-range shooting much easier to do under trying circumstances.
Last but not least, buy and learn to use a good laser range-finder. - I got one for just over 200 bucks, a sound investment as most of us cannot really estimate ranges past 100 yards all that well. If you use a range-finder, you won't have to guess after spending big bucks and crawling around in the rocks and cactus for hours.
- But that's just me. YMMV
Taking long-range shots at game is not easy, and mistakes affect both you and your quarry in a very bad way. - I want all of the advantages on my side that I can possibly get, for this type of hunting.