I can't believe these answers here......"If you can see it you can kill it???"......sounds like something on a "XXX Long Range" video.
First of all, what's "long range?" (350yds is truly long range for most people) whereas most of the shiney mags and the Xtranormal innernet warriors and Snipers will tell you that "long range starts at 600yds" so's I'm guessing from your description....correct me if I'm wrong.
Secondly, how ethical are you? And how good? Do you currently shoot "long range?" Like 600yds? Given a 12" kill zone there's not one hunter in 10,000 that can hit it with ANY GUN at 600yds let alone a "lightweight rifle."
I build and shoot rifles capable of 1/10moa to 1/4moa accuracy. These rifles routinely shoot groups 3"-6" at 600yds in the real world......With this sort of rifle could you hit a 12" disc at 600yds? HAVE you? (There's a HUGE difference between shooting a group onto a sheet of plywood at 600 VS hitting a 12" killzone with one shot)
Also, "deer and or elk,".......are you a CO native? Do you know how much harder elk are than deer? (I saw 30-06 w/168's mentioned. I'm in elk country too......and IME hitting an elk with 1200fp isn't ethical. Just my opinion. 'Course, my opinion also is that elk rifles for anything beyond 350yds START with 338/250gr.)
Not trying to rain all over your parade but I ain't jumping on this "build you a 300 and have at it" bandwagon, nor letting it pass by without more input from you.