Every group has a vocal cadre that demand compliance to their closely held beliefs as defined by their collective. In the AR-15 realm we have the mil-spec junkies. These folks have their short list of approved manufacturers and the moment a new company dares to come into existence they pounce to question every minute detail of the materials and processes used to manufacture the interloper’s new wares. Often times the criticisms leveled against the manufacturer’s products will be centered on compliance to military specifications. Ironically, most who cite the military specs for rifles such as the AR15/M16 have never read the actual specifications or even know where to find them. Instead, they resort to parroting what they’ve read on Internet discussion forums . . .
What are military specifications (mil-spec)? Simple; they’re standards established by the General Accountability Office (GAO) for defining essential technical requirements of purchased materiel for the military or for substantially modified commercial items to be used by the military. These standards have been established to guarantee interoperability, commonality, reliability and cost of ownership to ease the strain on logistics systems.
What mil-specs aren’t are a guarantee a particular product is the absolute best that it can be in terms of materials used, processes for manufacturing, etc. In the case of the AR15/M16 many of the specs were established in the 1960’s and 1970’s long before various modern alloys were developed or even before CNC machining was in common use.
Take the buffer tube (receiver extension) of the AR15 rifle for instance. The military standard tube has a diameter of 1.148”. A commercial buffer tube has a diameter of 1.168”. The threads are slightly smaller in diameter on the commercial tube (1.170’ vs 1.185”) as well. Some commercial tubes have welded end caps where mil-spec tubes consist of one piece.
Is the thinner mil-spec tube stronger than the thicker commercial tube? I guess that depends on what tests are conducted. In a real world application would a commercial tube be any more likely to fail if exposed to the same stresses as a mil-spec tube? Everything I can find indicates no, the mil-spec tube isn’t necessarily any more durable or able to withstand significantly more stress than the commercial variant.
So why do we have mil-spec on buffer tubes? Simple. If we go back to the definition of what mil-spec is, in this case it has to do with interoperability and compatibility. A soldier should be able to remove a buttstock from one M4A1 and drop it onto another M4A1 without having to worry about compatibility. That’s it.
Another example is the use of Carpenters 158 steel in the construction of AR15/M16 bolts. This goes back to the specs written for the M16 being drafted in the 1960’s and 1970’s. Carpenters 158 is the mil-spec standard material for manufacturing a bolt, but is it the best material available? Lewis Tool & Machine (LMT) thinks that Aermet is vastly superior (2.5 times stronger) to Carpenters 158. Their Enhanced Bolt, which is designed to remedy failures associated with the mil-spec standard M16 bolt, seems to be a popular item. Better materials exist now, but the mil-spec standards haven’t been modified.
All the mil-spec junkies will rant and rave that Carpenters 158 being a must. They’ll cite the infamous “Chart” hosted by M4Carbine.net as their holy bible on the subject. Yet in reality, Carpenters 158 is a minimum standard and nothing more.
Here’s how I view military specifications as it relates to the AR15/M16. It’s a good place to start. Period.
If you’re new to AR15s and don’t know what to look for when buying a rifle from one of the 50+ makers of AR’s out there today, stick with mil-spec standards to get started. Or, do your research and find out where deviating from the military specifications can be a good thing.
There are some specs you don’t want to deviate too far from such as MP/HP testing of bolts and barrels that assure quality and durability. Staked nuts on the gas key are a good thing as well. Having .154” diameter pins for the fire control group is another good thing (Colt used larger holes at one time). M4 feed ramps on a carbine are a bonus, too, as they improve feeding reliability.
Do your homework before making a purchase and you should do just fine when buying a new AR. But please, don’t get too caught up in the whole “if it isn’t mil-spec it isn’t s***” nonsense and avoid becoming one of “them”.
Tim Harmsen runs the Military Arms Channel