Originally Posted by
genofromreno
Email sent to you rapomstage3. Also double check the barrel extension to ensure it's a E3 configuration.
@mtdawg169: I also enquired about that upper. He said he bought it as a complete rifle through grabagun.com. Yeah KAC makes a lot of adjustments during any given product cycle to include marking changes, this is particularly prevalent on the rail systems. But I haven't seen a KAC upper that hasn't ever been marked though and this is going back to pre E3 days (M4, M5, Match, etc). After the switch over to the Mod 1 they did omit the laser etched KAC shield from the upper left hand corner on the non-ejection side. Buts it's still highly unusual for all the laser etching to be omitted. But like you said mtdawg169, you had one of the first commercial ones sold and it didn't have markings. I have a couple early legacy SR-15 E3 with the smaller gas port but those are marked.