Based on the specs of other 6.5 offerings I tend to see faster twist rates on barrel lengths less than 20", usually 1:7.5. Since it seems the 6.5 kits are still in development and could a faster twist barrel be offered?
It'll likely be possible, as they did with the 5.56 barrels initially offered in 1:9 and now also 1:7, that they can just produce a 2nd line of 6.5 barrels. It'll just take time. I just want a 6.5 XCR with the 18" barrel, a magpul UBR stock, and magpul MBUS sights. I can wait for them to tool up for the 1:7.5 barrel and buy it later as an addition