The RCBS small base dies are a must if you want to take preventative measures against any potential sizing issues. When I first started loading for the 6.8, I purchased the RCBS FL die set. At first they worked just fine. However, when I purchased my second 6.8 upper and started to load for it, rounds would get stuck in the chamber and not extract. After discussing the issue with some of the people here on the site, I bought a small base die set from midway. Ever since, I haven't had any problems with cartridges not extracting.