Many thousands of whitetails have died by the 243 win. The 6 creed is very similar ballistically. You will be fine. They used to have a January antlerless season in iowa that allowed centerfire rifles 24 caliber and larger. I killed dozens of deer with a 243 using 80 and 85 grain speer hot cores and 95 grain hornady sst and nosler bt. The ranges varied from 10 yards to 465 yards with many being in the 250-400 yd range. I had no problems with lost deer, and many were drt. I would imagine a 108 would do even better as long as the velocity is high enough to facilitate bullet expansion.