Aero Precision Assembled XL Upper Receiver for Big Bore AR-15 – Enlarged Ejection Port

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Faxon Firearms 16 inch .450 Bushmaster Barrel – Carbine Gas – 4150 QPQ


AR-15 Upper for Big Bore Calibers – .450 Bushmaster, .458 SOCOM, .50 Beowulf

If you’re planning a big bore build for your AR-15, one area that often goes overlooked is the upper.  The brass from .450 Bushmaster, .458 SOCOM,  or .50 Beowulf, won’t fit through a standard AR-15 upper’s ejection port.  Luckily, Aero Precision makes a forged upper receiver that solves this issue, with a port door sized for larger brass casings.

The XL Upper is just like your standard forged upper, with two key differences.  One, the enlarged ejection port opening, plus a laser-engraved “XL” on the rear tang.  Just to make it easy to distinguish from your other upper receivers.

Laser Engraved Tang and Enlarged Ejection Port

Forged From 7075-T6 Aluminum

Just like the other Aero uppers you can trust, the XL is Type III Class 2 hard coat anodized or finished with Magpul FDE Cerakote.  The 7075-T6 aluminum forgings are completely within spec in every other way, ensuring compatibility with other dust covers, forward assists, handguards and more.  The only real difference is the ejection port opening, and the distinguishing “XL” on the tang.


  • Port door opening enlarged to enhance larger diameter brass ejection (.450 Bushmaster, .458 SOCOM, .50 Beowulf, etc.)
  • Features Laser Marked “XL” designation on the upper receiver tang
  • Compatible with AR15 Lower receivers
  • Compatible with AR15 Port Doors and Forward Assists
  • .250 takedown pin holes
  • Includes port door and forward assist


  • MATERIAL: Machined from 7075-T6 forged aluminum
  • FINISH: Anodized Black or FDE Cerakote
  • COMPATIBILITY: Works with all Mil-spec AR15/M16 components
  • ENHANCEMENTS: Enlarged ejection port for big bore brass
  • WEIGHT: 8.35oz

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Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

Aero Precision Warranty

If for any reason you have a warranty issue with one of our products, please contact us at 253-272-8188.

Please describe your situation, include your name and order number or transaction id. One of our technical specialists will then review your claim and contact you within 3-5 business days.

If you have images to send, please email them to

Damaged Items

In regards to claims dealing with damaged or blemished products, we ask that you create a Help Desk Ticket on your My Account page. If you don’t have an account with us, please go to the Contact Us page and fill out the form for review within 72 hours upon receiving the shipment.

If you have images to send, please email them to

Failed Background Check

There will be a 30% restocking fee on all lower receivers returned because of failed background checks.

Disclaimer: Manufacturer’s warranty is subject to change without prior notice.

Customer Reviews

Based on 1 review
Phil Rizzuto
Its what I expect from Aero

Essentially the exact same as the standard AR that Aero makes except the ejection port lip is milled down to allow a larger casing (458 socom in this case) out. Honestly the mill work could be better because its not exactly even all the way around but it functions so I cant compain for the cost. A Faxon 458 socom barrel and Geissele mk4 handguard installed with no issues. Id order another if I was doing another big bore build.

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.