In case anyone has noticed before Constructor is a instigating prick.
Dare one of you trying that with him.
Cough cough he kind of took two different situations one was tagging me for being naturally paranoid of Mr Murphy!
The Xtreme barrel, as C has already pointed out, in the spots where most auto gun get tight with feeding are actually looser. The reason he recommends and I agree with using SBD is if you need or plan to be doing a large amount of very fast pace high volume shooting. Carbine class for instance. It is added insureance that you will have no issue as things starty to get gummed up with carbon and gunk.
As the Xtreme was put out as a combat focused upper the recommendation for small base dies is proper. In that type of shooting you want to take zerop chances. Most likely you would have no issue at all even in that type of shooting with regualr dies but why take a chance.
Many people are using the xtremes with normal dies without issue.,
THe same recomendation would stand for any 6.8 AR used for that typeo of shooting. IT IS NOT XTREME SPECIFIC.
Infact the XTREME is setup specifcally so it works very well with both handloads and factory ammo. Its headspace is kept near the min and the leade diameter size is reduced both of which help with keeping the bullet in line with the bore's centerline and reducing ther amount of case stretch and work hardening. Areas such as the base and neck diameters of the chamber are actually a tad larger than spec which helps with feeding with hand laoded cases that have a number of firing and were not sized as much.
This end up giving you a barrel and chamber that not only maximizes accuracy but also improves feeding. Constrcutor shoudl get full credit for the chamber as he has learned very well from all of my teachings. Way to go grasshopper!!
Seriosuly now, the chamber used in the Xtreme was purposely made to work very well with all ammo and give maximum relaiblity yet still keep accuracy near max. It is a improvment over the SPCII and other chambers out there for both handloads and factory ammo. Infact is is proably one of the best for factory ammo. Our chambers are held to very tight tolerances.