Your insight will be appreciated, but in your off in saying you can't be an efficient shooter at 1000 yards with a tactical rifle. Chances are the guys you saw failing weren't proficient to begin with. With practice and load development I have no doubt my LaRue could easily hit 1000 yds with decent groups. It has a 20" barrel. I have never seen that distance, nor plan to. I don't train professionally for that distance. But I took it out to Arizona to meet up with some members here, walked it out to 550 yds shooting steel, having never shot farther than 300 prior. There was a learning curve, but with practice I have no doubt it can be done. (Especially since on the magpul dynamic training videos they were doing it with a 16" barrel consistently)
You first post came across a bit crass, and you drew the wrong end of the shit stick for replies. Some people do build/buy these rifles for those distances, and have success. It may not be common from what you've seen, but it can be done