Coronado Arms Unveils New Extended AR-15 Upper Reciever


One of the main issues with the AR-15 platform is that the rail on the top of the upper receiver is simply too short for most optics. You can cheat and use a cantilever mount to shoehorn your glass on there, but it sn’t an ideal solution. Now, Coronado Arms is coming out with an extended upper receiver that gives you enough rail to mount your optics firmly and seperately. They’re planning on shipping shortly, and we’ll have one of the first ones off the line to test out.


  1. avatar Clint says:

    It looks cool. How is this different from Aero Precision’s upper?

    1. avatar K-Bizz says:

      I was about to say…

  2. avatar OCD says:

    Why, exactly, is a cantilever mount not an ideal solution?

    1. avatar Tom of Toms says:

      The problem is in the name – “lever”. As in “leverage”. It can NEVER be as robust as a system that supports a scope’s mounting points from end-to-end. Imagine a rifle tipping over and landing on the objective-end of the scope, which happens to be hanging out on the leverage-end of the cantilever mount. There is most definitely an opportunity for bending there, resulting in loss of zero.

      1. avatar Ian T says:

        Perhaps if your mount is made out of paper-mâché, but any decent cantilever mount made with good steel or aluminum will withstand that no problem. If your scope doesn’t break, then your mounts shouldn’t either, even with how robust scopes can be.

    2. avatar Max says:

      My thoughts exactly. What is so “bad” about a cantilever that I would want to spend (probably) a few hundred dollars on a new upper that will also require me to buy a proprietary rail for ANOTHER couple hundred dollars…

  3. avatar Ralph says:

    The AR platform wasn’t designed for optics. It was a soldier’s rifle, intended to be used with iron sights.

    The brilliance of the design is shown in its adaptability as a civilian firearm, using all kinds of optics mounted close to the bore axis once that “carry handle” was removed.

    1. avatar maynard b says:

      It was a soldier’s rifle, intended to be used with iron sights.
      Just like Mausers! Optics on Mausers is a flash in the pan…

  4. avatar Hkfan says:

    What are you talking about about? A bobro or LT extended mount works perfectly fine and has been used in the field for years.

    1. avatar Tom of Toms says:

      “Works perfectly fine” is not synonymous with “ideal”.

      You pay good money for those Bobro mounts and their high quality materials and engineering. They’ve overcome an obvious shortcoming with material and technique. I never said they are “worthless” or “unuseable”, but merely provided insight (in the form of a simplified and easily visualized example) as to why, when all other things are equal, a mount that is secured from one end to the other has the potential for greater strength.


      1. avatar Hkfan says:

        Except, with their materials and engineering, there is no loss in zero. These quick detach mounts have been tested thousands of times without any impact on zero. There are numerous white papers on this. This is old news.

        1. avatar Tom of Toms says:


  5. avatar JW says:

    Spell Check, Nick, Spell Check!!!

    I before e except after C

  6. avatar Arod529 says:

    I didn’t realize this was a problem… but then again, I don’t tend to put oversize scopes on a combat rifle.

    1. avatar Hkfan says:

      I’ve got a scope with a 56mm bell with no issues.

  7. avatar Kevin1911 says:

    This won’t be anything new. Colt, Aero, LMT and Vltor all have similar offerings but if this is a keymod upper that would be a bit different.

    1. avatar Diesel Dan says:

      I’d much rather put a Midwest Industries K-series keymod forearm on a decent “standard” AR15 instead of a $2300 Coronado AR.

  8. avatar stormchaser says:

    I was considering an upper in monolithic style with free-float, this could be one choice.

  9. avatar Dyspeptic Gunsmith says:

    It sometimes amuses me how much effort people both within the DOD/defense industries, and out in the private sector, have sunk into turning the M-16/AR-15 into a “real rifle.” Add a gas piston. Make it shoot something larger than a squirrel cartridge. Give it optics. Make it a long range rifle. Make it a sub-machine gun. Make it a carbine. No one seems to stop to ask “Do we want a dessert topping or floor wax?”

    No, it’s always “Let’s try to make it both!” And what we get is a sticky floor wax and a really obnoxious-tasting frosting, but hey, we look “operator as (*&^” doing it!

    At some point, someone’s going to have a brilliant idea: “Hey, I know! We’ll start with a clean sheet of paper and design a gun that is designed to be a real rifle!”

    I figure it’ll happen in under 10 years or so, but I don’t believe this strongly enough to bet on it.

    1. avatar Diesel Dan says:

      Well, a M4A1 lower with a Faxon ARAK-21 upper chambered in 6.5 Grendel sounds pretty damn nice to me.

  10. avatar Jim says:

    Not sure why we’re all complaining about a new offering. It looks like a nice receiver. It may not be a brand revolutionary idea, new idea, but it allows you to directly mount an optic with simple, inexpensive scope mounts. Personally, I like to have several options to choose from.

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