A Remington 700 VLS 26" SS .308 2002 Limited Run Rifle has a 1 in 12 twist? If 1 in 12 is correct recommended bullet weight for long range (300 to 600 yds) 168gr-185gr?
300 to 600 yards is mid-range. 800 to 1000 yards is long range. For mid range shoot something like a 175gr Sierra Matchking. For long range, you can change to the 190 gr Sierra Matchking. Another good choice would be the new Sierra Palma bullet. It has the same ballistic coefficient as the 175 gr, but can be pushed about 200 fps faster. Any of the 3 bullets mentioned will make it to 1000 yards while supersonic which is a requirement for accuracy.
I am sure that you noticed that the 168 wasn't mentioned. The 168 Sierra is a very accurate bullet, but it was designed for 300 meter shooting and is not as streamlined as the others. If fact, the 168 and the 175 can be pushed to about the same speed, but the 175's BC is much higher and therefore it will hold the wind much better.
A 1:12" barrel will handle any of the Sierra Matchkings up to and including the 190 gr in the .308 Win.
Having grown up hunting with a 30-30 100 -125 yrds (longest shot made/taken) was a long way and average shot was 35 -50 yrds. With that said 300 - 600 yrds is a long way for me but I hope to try and stretch the .308 in the next couple months.
I'm just getting into rolling my own so I'll apologize up front for questions that may follow. Currently I have only shot Remington® Express® R308W1 150gr Pointed Soft Point Core-Lokt® for hunting applications out to 100yds and I'm sure it isn't up for the 300 -600 stretch (although I haven't tried it). Most of all I need time behind the rifle at distance.
Maybe I should let one of you guys give it a run and tell me if I am wasting my time...