Forget 180gr bullets, there are none out there with a high BC meaning you will have squat for energy at 300 yards.

Your best choices right now for a 300yd shot are a 200 or 300gr Shockwave (the 250 is the worst choice of the 3 weights, ballistically), perhaps a 240-260gr Dead Center, or a Barnes TMZ. A newer option is either the 265gr .430 or 325gr .458 Hornady FTX (flex-tip) that can be bought in bulk.

Whatever you use, drive it as hot as you can shoot tiny groups. If you can't shoot sub-1.5 inches at 100 yards, forget it and work up a different load.

It's one thing to find a load that has good ballistics to 300 yds (forget about thinking there is one out there requiring no hold-over, these are not centerfires). It's another to have a gun that shoots as well and repeatably as you need it to. And quite another to take the time and discipline to make sure you can shoot the way you need to -- FROM FIELD POSITIONS -- not from a bench. If you're going to shoot 300 yards, you'd better be on a bipod or in a blind with a table and bench setup.

And the one thing noone has mentioned yet -- WIND. Drop is easy, get a rangefinder and a chart based on proven drops at the range and you are good to go. But do you know how far a 5mph wind is going to drift a ML shot at 300 yds? Enough to be a problem, so you have to be able to gauge the wind and compensate for that too!

I've killed a few deer past 300 yards, all bang-flops. But I rarely bother shooting my ML at 100 yds, when I get range time it's all 300-400 yd shooting. Getting an accurate, flat-shooting load is only the first step.