Re: 6mm Rem. for long range 700 m - 1000 m ?
The 6mm will do fine at 1000m as long as you are using the right bullets (100 grain to 107 grain) and youre not shooting at big game. A few people swear by the 243 AI for antelope and such, but most are sckeptical. As far as killing paper or vermin, it is a good round. Those 107 SMK's have a decent BC and you can drive em to about 3000 FPS. This is about on par with shooting a 308 palma load (except for the energy). You will need to check your twist to see if it will handle the longer 107's. If not, 100 grain SPBT work well too.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.