I am in the market for a 300 Blackout upper and have always wanted a Knights Armament AR. I see that these have been fazed out and can be had for discounted $$ which in the KAC world is not the norm. Please  I am only looking for reviews of this upper and not recommendations for other uppers at this time.
One thing Of notice with the KAC is a carbine length gas tube in every upper except the 9.5 and was under impression that pistol length was recommended when shooting subsonic blackout suppressed.
The help from the vast knowledge of ar15.com is appreciated.
R

Pistol length is much better for the 300 blk, the carbine length systems are known to have cycling issues with subs.