There are many options out there when building your own custom AR15. Calibers, manufacturers, barrel lengths, accessories – all relevant considerations. We’ll do an Aero Precision AR15 review and tell you your best build options.

Why choose Aero Precision lower receivers and Aero Precision parts?

Simply put – choosing Aero Precision over other manufacturers means you’re choosing quality. Other manufacturers claim they meet mil-spec requirements – but two days in the field with some Marine Corps grunts would show you otherwise.

Aero Precision offers a wide range of products. The Aero Precision M4E1 lower receiver and Aero Precision X15 lower receiver are great examples of Aero Precision’s ingenuity and quality.

Choosing an Aero Precision BCG, upper and lower receivers, handguards, or lower parts kit will mean the difference between maintenance after 5,000 rounds or 10,000 rounds.

aero precision APRH100968, lower parts kit

Worth Firearms also sells AR-10 parts. Check out our review for Aero Precision’s AR-10.

Aero Precision AR15 Review: X15 vs M4E1 lower receiver

The primary difference between the Aero Precision M4E1 and X15 receiver sets are the built in features of the Aero Precision M4E1 lower receiver.

Aero Precision M4E1 Platform

The Aero Precision M4E1 lower receiver features a:

  • Threaded Bolt Catch Pin
  • Integrated Trigger Guard
  • Upper Tension Screw
  • Threaded Takedown Pin Detent Recess
  • Increased Magwell Flare
  • Marked and milled to accept short-throw and standard safety selectors

Pro’s of the Aero Precision M4E1

  • Threaded Bolt Catch Pin and threaded bolt catch
  • Integrated Trigger Guard
  • Threaded Takedown Pin Detent Recess
  • Marked and milled to accept short-throw safety selectors and standard selectors

Con’s of Aero Precision M4E1 lower receivers

  • More expensive than X15
  • Not usually available in OD Green or Burnt Bronze

Aero Precision X15 Platform

The Aero Precision X15 lower receiver features a:

  • Upper Tension Screw
  • Increased Magwell Flare
Aero Precision, od green ar-15, stripped lower

Pro’s of the Aero Precision X15

  • Upper Tension Screw
  • Increased Magwell Flare
  • Available in more colors (like OD Green, Burnt Bronze)

Con’s of the Aero Precision X15

  • More expensive than similar models (better quality than these brands though)
  • Potential damage from using a hole punch versus the threaded bolt catch pin in the threaded bolt catch hole

What is the 4-40 set screw Aero Precision?

The 4-40 set screw makes changing the buffer tube and stock for AR15 easier.

Without the set screw, you’d take the end plate off and decrease the tension placed on the detent spring holding the rear takedown pin.

With the screw, you can work on your lower receiver without worrying about the receiver endplate and the rear takedown pin or detent spring coming out.

A quick summary of steps (or watch the video below):

  1. Buy an Aero Precision Lower Parts Kit
  2. Buy an Aero Precision Buffer Kit
  3. Insert the rear takedown pin with the channel facing the rear of the lower
  4. Insert the rear takedown detent into the lower receiver
  5. Insert the rear takedown pin spring into the lower receiver
  6. Remove enough of the springs so just a few coils stick out from the receiver (use snippers for this)
  7. Insert and screw in the 4-40 set screw.

This feature is available on the Gen 2 Model X15 and the M4E1 lower receiver.

threaded roll pin

Is Aero Precision lower mil-spec?

Aero Precision m4e1 lower receivers and Gen 2 X15 lowers are mil-spec dimensions with some extras.

Two of my favorite features include the threaded bolt catch pin and flared magwell.

Threaded Roll Pin

The threaded roll pin for the bolt catch is a lifesaver. Using the threaded bolt catch pin will save you from marring your receiver when installing the roll pin. Both Gen 2 X15 and M4E1 lower receivers include the threaded bolt catch pin system.

Again – without this system, you’d need to use a hole pin punch to nail it into the bolt catch pin hole. Using a 6-32 hex key, you can easily install the threaded bolt catch pin without risking damage to the finish of your receiver.

This can be easy to lose – along with any detent spring or detent. These parts are available for purchase separately as well.

Is Aero a good AR brand?

Aero is usually considered a mid-high tiered brand. In our opinion, they’re a top AR15 custom build brand. When compared to a higher end factory built rifle, you’re going to start seeing some small differences.

However, it’s all in the materials you build with. If you add a poor performing barrel, your rifle won’t run nearly as well as a budget factory rifle with a superior barrel.

Looking for a bolt carrier group? See our recommendations.

This is why we recommend ballistic advantage barrels – their sub-MOA guarantee will give you a good jump-0ff point for a well running rifle. But don’t forget to buy an upper receiver.

Also – keep in mind the following factors:

  • Your shooting skills – are you proficient?
  • Was the rifle assembled correctly?
  • Can you tweak the rifle settings (i.e. – upper tension screw, adjustable gas brake, better ammunition) to make it more accurate?

Luckily, there’s a chance to get Aero Precision free shipping on our parts. Spend more than $100, and we’ll ship it to your FFL for free.

Which should you buy

The next question – which AR15 platform should you buy?

Our suggestion?

  • If you’re new to building AR15 rifles and can afford it, go with an Aero Precision 556 style platform like the M4E1 platform. The added features will make building, modifying, or upgrading much easier.
  • If you’re looking at it from a budget perspective, go with the Aero Precision X15 platform. Parts are cheaper and still have some added features you’re sure to appreciate.
  • Purchase the parts as a receiver set – you’ll save money compared to parts purchased separately.
  • Colors – the Aero Precision X15 has more colors available. It’s easy to do an Aero Precision complete build when you buy everything as a set.
  • Performance – both rifles will perform well. Be sure to find high performing ammunition, barrels, BCG’s, and comfortable furniture.
  • Save EXTREME amounts of money – go BLEM. BLEM lowers run just as well as factory new but do not carry a warranty and have minor cosmetic defects.

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