i have fallen in love with the idea of a 10.5" sbr but i want something that can reliably perform well out 100 yards and maybe even 150. i dont think a 10.5" 5.56 can do much better than 50yrds with fragmentation thresholds of even 5.56 tap. so what caliber? 6.8, .308, 6.5, or the new 300 blk ? i dont really know what im doing i just need pointed in the right direction. am i chasing a pipe dream thinking i can build a 10.5" that can still have effective ballistics out at 100 & 150 yards? also if any one knows how mk318 sost ammo will perform out of a 10.5", that info would be greatly appreciated! thanks again guys.