I'll jump in and say, the smart move, having shoot a lot of prs and done a little shooting game at long range, I would get something small to medium sized that is comfortable to shoot. After you have burned out a few barrels, add a big boomer and stretch it further.
More recoil is harder to shoot well and more expensive to practice with. I have several stocks, tl3 actions, and a bunch of barrels. I also have a rimx 22lr. Shooting 2k-5k centerfire rounds and 7k-25k rimfire rounds per year goes a long ways toward hitting things. I could never afford to shoot that much with a 300 mag. It is a lot easier to stomach with a 223 and a 22lr.
There was a benefit shoot this spring with an ipsc at 1407 yards and 1760 yards (1 mile). I was shooting a 28" 243 Ackley with 115 dtacs at 3150 fps. I hit the 1407 yard target on the second through 5th round. My wind call was right but my dope was high on the first shot. After that I went to the mile target. It was A LOT harder to hit. I managed to hit it a couple times in 10 shots.
My point is, 1200 yards isn't as far as you think. You do not need a 300 mag to ring steel at 1200 yards. Get something short action and get multiple barrels and bolt heads for it. Get a 223 barrel and a 6.5 prc or 7 saum barrel if you want something big to mess with. Get a barrel vice and action wrench and you are all set. You need to be able to practice to be proficient at long range killing. A magnum cartridge will not be a sufficient substitute for practice. The beating and number of barrels to get sufficient practice with a 300 mag is significant. Not to mention the ammo cost. Most people will not do it even if they have the time and the money.
More recoil is harder to shoot well and more expensive to practice with. I have several stocks, tl3 actions, and a bunch of barrels. I also have a rimx 22lr. Shooting 2k-5k centerfire rounds and 7k-25k rimfire rounds per year goes a long ways toward hitting things. I could never afford to shoot that much with a 300 mag. It is a lot easier to stomach with a 223 and a 22lr.
There was a benefit shoot this spring with an ipsc at 1407 yards and 1760 yards (1 mile). I was shooting a 28" 243 Ackley with 115 dtacs at 3150 fps. I hit the 1407 yard target on the second through 5th round. My wind call was right but my dope was high on the first shot. After that I went to the mile target. It was A LOT harder to hit. I managed to hit it a couple times in 10 shots.
My point is, 1200 yards isn't as far as you think. You do not need a 300 mag to ring steel at 1200 yards. Get something short action and get multiple barrels and bolt heads for it. Get a 223 barrel and a 6.5 prc or 7 saum barrel if you want something big to mess with. Get a barrel vice and action wrench and you are all set. You need to be able to practice to be proficient at long range killing. A magnum cartridge will not be a sufficient substitute for practice. The beating and number of barrels to get sufficient practice with a 300 mag is significant. Not to mention the ammo cost. Most people will not do it even if they have the time and the money.