citizenconn
Member
There are also a lot more enhancements on the Aero "enhanced" version such as a screw in threaded bolt catch roll pin, screw holding the rear takedown pin spring instead of relying on the buffer end plate, a tension set screw to adjust the fitment between the upper and lower receiver, a flared magwell, and a higher quality coating on the lower. Plus as you mentioned the closed trigger guard. Overall there is a lot less banging with a mallet to put these lowers together which is a great thing. I have seen more folks break off the trigger guard ears with a mallet on standard lowers than I have fingers or toes.The M4E is a good lower. They are still high quality 7075 Forgings made by one of America’s Foundries. Aero just machines the lines & angles with CNC, to imitate the looks of a Billet. What I do like is the closed trigger guard.
Ballistic Advantage enhanced lowers are made the same way (probably in the same facility, but I don't know) as well and are also a good option.
https://www.ballisticadvantage.com/ba-ar-15-enhanced-lower-receiver.html