There are a plethora of options when it comes to lower receivers for the modern AR15 builder. From plain milspec versions to fancy billet aluminum versions with complicated millings, there are receivers for every builder at every price point. Today we're going to take a look at a very popular (and good looking!) option: the Aero Precision M4E1.
The M4E1 is the more premium of the two lower receiver offerings from Aero Precision. (The other is the more basic lower receiver that is milspec in all regards). As such, it offers a few premium features over a standard milspec reciever that make it more visually appealing, functional, and easier to build. MSRP for the M4E1 is 145 dollars, but it can easily be found on sale. I got this one at Brownells for about 125 dollars.
Now for some basic specs: the M4E1 is forged, not billet, which keeps the cost down. It is forged from 7075-T6 aluminum. This puts it above receivers that are made from 6061-series aluminum, as 7075-series aluminum is notably stronger. Aero then finishes the M4E1 in either black anodizing or FDE Cerakote that is a close match for Magpul FDE. The receivers are marked with the Aero Precision "A" logo on the right side of the magazine well, and with a multi-caliber designation and serial number on the left side of the magazine well. One more notable marking on the receiver is for the safety selector, which is designed for short-throw 45-degree selectors that are popular among builders. (The M4E1 will also accept standard 90-degree throw levers, but the markings on the receiver will not line up when a 90-degree selector is installed).
This marking for a short-throw safety is just one of the features that Aero has included in the M4E1 with builders in mind. My personal favorite is the threaded bolt-catch pin. For those of you that have ever assembled a lower receiver, you already know how easy it is to scratch or damage the receiver when trying to install the botch catch roll pin. By threading this pin, Aero has made this step of assembly so much easier: just drop in the spring and bushing, put the bolt catch in place, and press the pin in by hand until the threads catch. A few quick turns of an allen wrench and the bolt catch is installed with minimal effort and no damage to the receiver.
Another builder-friendly feature that Aero has thrown in is threading the rear takedown pin detent hole for a set-screw. This allows the installation of the buffer tube, rear endplate, and castle nut assembly without having to hold down the detent spring or risking tweaking the spring on the endplate.
As far as functional and aesthetic features go, the M4E1 has those covered as well. The most obvious of these features visually is the overall "billet" aesthetic of the design. There are lots of sharp angles and lines that give the look of a billet receiver, but come at the more palatable price of a forged
receiver. Another great visual feature that Aero includes is the large flared magazine well that aids in fast reloads and magazine seating. Another of these features is the skeletonized integrated trigger guard. By building this into the lower receiver, Aero again eases the building process while simultaneously providing a strong but light trigger guard. The final feature that Aero builds into the M4E1 lower is a dedicated tensioning screw that allows the builder to adjust the amount of tension that the lower receiver has against the upper receiver; this eliminates the "wiggle" that sometimes happens between upper and lower receivers.
There are so many options for lower receivers for the modern AR builder that choices can sometimes be overwhelming. It is easy to get caught up in flashy features or billet style, but the M4E1 delivers many of these desirable features and aesthetic while keeping to a very affordable price point. Overall, I think it is a very solid choice for a lower receiver. If you're interested in the M4E1, you can pick one up at Brownells.
That's everything I have for you now, but don't forget to check out the channel where I release videos every week on lots of practical content. Until next time, stay safe!