These guys are right on, but let me give it to you from the perspective of more or less a newcomer to the LR scene. until just a few years ago a deer killed at 300 yds or better was cause for a celebration. Then being a gun nut anyhow I decided to have a custom rifle
built, Mark Bansner of adamstown pa built me one of his rifles on a rem 700 chambered in 7mm STW, accuracy was awesome, over the next several years, the 300 yd shots were wonderfully simple. Then I started studying ballistics and when ballistic programs for the home computer became popular and I understood how to use them I concluded that I could in fact make the unheard of 500 yd shot with my STW without making any adjustments to the scope. Just 19" of holdover and the deer was in deep trouble. 4 years ago I had premier install target turrets on my 6.5x20 leupold, now I can dial it in, however the extremely light barrel and configuration of my Bansner UR-1 is diffacult to shoot in field positions so my self imposed limit with this rifle is 625 yds.
Scince 1998 I have shot at a total of 18 deer at 400 yds and overout to 627 yds. 17 shots have been fatal hits with no tracking. The 18th one well the first time dialing my scope in I screwed up on a doe at 489 yds, and over shot the intended target but killed one standing just beyond it. Its not that diffacult once you have confidance in your shooting system and your own abilities, but you must,I repeat this YOU MUST work within your limitations.
I now wait for kirby to complete my new LR rifle so I can go into the next phase of LR shooting, and am looking forward to it.
10 years ago you couldn't convince me that a 223 rem could be lethal on chucks beyound about 380 yds. With what I have learned from these guys here and picked up through practice in the field, I know my lowly AR-15 will take chucks to 600 yds. confidance in your equipment and your own abilities will take you along ways.