If your Armalite serial number has 4 digits only then it's not an original Armalite SuperSASS. When we bought Eagle Arms back in 1994 (if I'm remembering the date correctly) our first serial numbers were 5 digit. 4 digit serial numbers were used by the prior Eagle Arms owners so the lower receiver should be an Eagle Arms lower receiver, not an Armalite. This sounds like the SuperSASS upper was added to your lower receiver. I'm assuming you're not the original owner.
It actually has 6 digits as the "0" would be considered a digit. The "B" being part of the serial number as well. When you stated "4 digits" that led me to believe it was an Eagle Arms.
Nothing has changed for the SASS except the barrel twist has gone from 1:11.25 RH to 1:10 RH twist in January 2011.
Say TR, what do you think about starting a thread and telling us about all the new additions to the Armalite line, and how you feel they have improved the product? It would be nice to hear and read more than just the sales material.
Ask away and I'll see what I can do to answer questions to the best of my ability. I don't always get a chance to come here as I have other duties as well that take up most of my day.
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