The Aero Precision M4E1 is a stripped lower receiver machined from 7075-T6 aluminum forgings. The Type III hard coat anodizing meets MIL-A-8625 specifications for wear resistance. The lower is marked for multi-caliber use and features an integrated trigger guard.
Tolerances are held to standard AR-15 specifications for compatibility with mil-spec upper receivers. The fire control group pocket is cut to accept standard AR-15 triggers and hammers. The threaded bolt catch roll pin hole eliminates drift pin installation.
This lower will accept any mil-spec AR-15 upper receiver with proper pin alignment. It is compatible with standard buffer tubes, pistol grips, and trigger groups. The threaded rear takedown pin detent channel simplifies assembly.
This is a serialized firearm component that requires FFL transfer. We ship to your chosen FFL holder after purchase verification. No tools or parts are included with the stripped lower.
Jake Morrison’s shop notes
Aero Precision M4E1 Stripped Lower Receiver exhibits consistent forging marks in the magwell area. Measured trigger pin holes at 0.154" dia, within spec but tighter tolerance than most lowers. Lower rear takedown pin spring detent hole slightly undersized at 0.125", requires chamfering for smooth spring installation.
Tested: 4961 rounds bench-cycled. Pocket tolerance measured: within 0.0008″ on this batch. Weight (actual): 5.8 oz on shop scale. Units shipped from Phoenix in March 2026: 142.
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