6.8 spc or 264 lbc

[Death Dealer]

Building a new upper and will be ordering one of these two in an 18" barrel. Look pretty much the same to me just looking for feedback from anyone who may have either one. Looking for pros and cons. I understand that the 6.5 grendel and the 264 lbc are one in the same.

[Tommyh]

18" isnt enough for good grendel breathing and really too long for 6.8. Id go 6.8 in ar platform tho.

[WKH2213]

This 18" 6.8 shoots lights out.
Holes touch at 100yds, about a 1.25" group at 300yds.
6.8 was designed for 16", but the 18's work awesome too.