“Mil Spec” is a term that gets tossed around frequently in the AR 15 community, and it’s often built up to this almost-mythical level of praise. But, the big question is, what does mil spec mean and, more importantly, does it even matter? Mil spec as a term gets used so frequently that it can be hard to separate the actual literal meaning from those who want to discuss the plethora of military-style custom AR parts, from which tactical grip is sturdiest to which KeyMod handstop and handguard rail work best together. The most literal definition of mil spec is standard for various firearms set by the US Department of Defense. Often, mil spec and MIL-STD (military standard) are terms used interchangeably. However, many AR 15 owners will use mil spec to describe custom AR parts that strive to reach the same specifications as actual mil spec.
So, here’s the thing, any commercially produced AR 15 is, by the strictest definition, not a mil spec firearm. Mil spec firearms have to meet certain standards set by the DOD before the firearms are handed over to our troops and are produced by government contract. It is possible to get a hold of the MIL-SPEC handbook which describes the technical requirements for the M16 (the military’s version of the AR 15) right down to the measurements and materials required. However, even making a part that directly matches the component in the handbook, does not make it mil spec. Any commercially available custom AR part, from tactical grip to the bolt carrier group, is not actually, literally, mil spec. Unless it is produced for the US military, an AR 15 is not mil spec - and actual mil spec firearms are very costly and practically impossible to get a hold of.
That being said, many AR owners appreciate the interoperability in the mil spec designs and are interested in these components for their ARs. Thanks to the AR’s easy customizability and the availability of the previously mentioned MIL-SPEC handbook, it is possible to modify your AR with custom AR parts that are made to military specifications. Again, in the strict sense of the definition, these custom AR parts aren’t actually mil spec, but it is possible to get a wide range of components, from the bolt carrier group right down to the M4 feed ramps, which are made to the same specifications as the components for the M16.
So, does it matter whether every part of your AR 15 meets mil spec? Honestly, that’s up to you and your preferences. As long as you’re keeping it legal, make your AR as close to mil spec as you want! However, don’t feel like you need to be shoehorned into an all-or-nothing mindset. Customize your AR 15 to work the way you want it to, which may mean swapping out that tactical grip for a KeyMod handstop. For the best custom AR parts, shop RailScales selection of handguard rail scales and MLOK and KeyMod handstops online today!