Just bought an upper made by RRA and I noticed that they are 1-10" twist.  The website shows that they have the spec II chamber.  I bought the upper off Gun Broker a few weeks back and it is new.  My question is––does anyone know if RRA ever used the older inferior chamber?  Or have they been making them the SPCII the whole time?  Reason I ask is I curious if there is a possibility that I got some new old stock with the crappy chamber.  With a 1-10 twist and the spec II  chamber I'm still safe with the combat loads right?  What is the rundown on this twist rate change and ammo pressure difference?  This is my first 6.8 so sorry if these are lame questions.  Thanks

I asked the same questions when I was looking at my RRA 6.8. Your GTG with the Spec II chamber and 1 in 10. I got that info from Cold who's opinion and back ground in the 6.8's development history I trust.

My RRA 6.8 (it's getting a total rework tomorrow):