SCREW MODULARITY, LET’S JUST BUILD INDESTRUCTIBLE GUNS

Aero Precision C.O.P. kit, or Continuous Optics Platform. This is as modular as a true monolithic design can be.

One of the interesting trends to come out of SHOT Show 2016 was the resurgence of monolithic upper receivers, or variants upon the theme of monolithia.  Monolithic uppers, for those of you who haven’t been especially interested in AR-15 trends, are ones in which the railed hand guards are permanently attached to the upper receiver, rather than the conventional method of clamping them to the barrel nut.  It’s a stronger system, but it’s also less modular, and since AR owners never seem to agree on what an ideal rail should look like, it’s a bit limited. Depending on the specific design, it can also make barrel replacement difficult, which seemed like a big problem a few years ago, but as the push towards quick-change barrels has been all but abandoned, how much of a concern this is may be judged by the individual.  Lewis Machine Tool’s Monolithic Rail Platform, or MRP, has a patented workaround, but we haven’t seen many people make use of it.

The last time the market surged towards monolithic guns was about five years ago, after the success of the aforementioned LMT MRP, and the VLTOR VIS, or Versatile Interface Structure.  If you reach back to 2010 or so, you’ll remember everyone talking about the monoliths, but the idea remained a niche concept after early flirtations with mainstream AR construction, largely because the market was more interested in modularity than ultimate strength.

Colt Canada's monolithic guns are among the cream of the crop.

So why are monolithic systems making a comeback?  Well, first, let’s get technical: not all of the systems we’re going to include here are actually monolithic.  The Colt Canada IUR and MRR uppers, which we unapologetically recommend, are true monoliths, as is the still-in-production (and highly successful) LMT MRP, and the Aero Precision Continuous Optics Platform.  There are vast numbers of other options in the true-monolith department, and they’ve all got their strengths and weaknesses.  The big strength is typically…strength.  Weaknesses are mostly the same: lack of modularity, difficulty of manufacture, difficulty of service and the need for special tools.

But what about the new, hybrid-monolithic uppers?  This is where things get interesting.

We looked at a couple of systems, one from Daniel Defense, and one from Aero Precision, that are not quite monolithic, but neither are they standard barrel-nut-mount handguards.

Aero Precision's Enhanced Series Upper has a splined extrusion which mates with their various handguard options.

Slid together, the Enhanced Series Upper displays tight tolerances and a superior mounting system.

Let’s start with the Aero Precision.  Their new Enhanced Series Upper, instead of a short threaded section at the business end onto which the user screws a barrel nut, has a splined extrusion with drilled and tapped holes which line up with their modular hand guard series.  What’s the advantage of mounting the hand guard in this manner?  Simple: rather than clamping it overtop of a nut, which can be misaligned, and which can generate stretch in the clamping section of the hand guard, and specifically in the raised gas tube cutout on the top rail, this bolts the rails directly to the upper.  It’s a clever system, and Aero Precision has a long history of great machining, so the execution is flawless.  We couldn’t believe the tight lockup on the ones we handled at the range.  It does limit you to the Aero Precision hand guards, but they make different patterns, and different lengths, for traditional Picatinny rails, KeyMod attachments, and what’s rapidly showing itself to be KeyMod’s replacement, the M-Lok system.  Barrel tightening is accomplished through the use of a supplied nut and wrench, and away you go.

Daniel Defense has taken a slightly different route, and so far this system has only been featured on their 7.62 AR, the DD5: they machine the upper with external bolt holes to allow their proprietary hand guards to be bolted directly to the upper.  In theory, this would allow for a similar degree of modularity to the Aero Precision system, although that’s dependent on Daniel Defense’s willingness to make a wide range of rails.  So far they haven’t been quite as interested in covering all the bases, although they’ve accepted M-Lok as of this year (though not in this pattern yet).  Still, the possibility for a few options could exist, should they opt to support it.

Obviously, the downside to these semi-monolithic platforms is the reduced modularity, and we’re sure that we’ll be hearing from people who point out that these new systems have the worst of both worlds: limited modularity, without the sledgehammer rigidity of a true modular upper.  We don’t disagree; you’re giving up something, and getting something.  What you give up is less than with a true monolith, but what you get is less ultimate strength.

Daniel Defense's DD5 offers a similar mounting system. Again, some degree of modularity is available.

Still, if you bought a monolithic KeyMod upper because you liked the strength, and the entire mounting system fizzles - and the death is slow but it’s happening - you’re stuck with a legacy system which thankfully should be supported for a pretty long time on the secondary market, but it just might not be what you want anymore.  If you had any degree of modularity, the fix would be cheap and easy.

The Daniel Defense attachment system has potential and we’ll have to see where they go with it, and if it makes it onto their 5.56 guns.

The Aero Precision Enhanced Series Upper, however, are ready to go right now, as are a range of hand guard options.  And our experience with Aero Precision has been sufficiently positive to warrant a recommendation.  If you want near-monolithic strength while retaining some flexibility in your hand guard options, we’re calling it for Aero Precision.