Actually I have been looking at the 6.8mm SPC but haven't invested any money into that cartridge yet. I haven't been able to find Blackhills in the valley yet, but Wilson Combat sells it online and I found a small shop in prescott that sells it also (can't tell ya name or address through, it's been awhile).
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"Trust in God --and press-check. You cannot ignore danger and call it faith." -Duke