Notes regarding milspec

[Battle Arms Dev]

Milspec is a word often misused and abused, sometimes people use it to cover a lot of areas when they do not have specifics.  When it comes to the AR system, this pretty much means TDP.  Sometimes it's not feasible, and impossible to produce civilian products using military specs.  Receivers may adhere to many milspecs, but not all of them.  Selector is another one.

Since we spent a great deal of time on the development and refinement of our selectors, I can chime in on the selectors.

The military spec selectors are decidedly NOT the same as any semi auto version, aside from the obvious select fire vs. semi only aspect.

Milspec M16 selector's detent groove goes 360 degrees, even to where there is no detent hole.  We can only think this was meant for a 4 way fire control group, it serves no other purpose otherwise. 

Semi auto selector's detent groove goes 90 degrees.

Milspec M16 selector's detent holes are bi-directional, in that you can rotate the selector either way when the detent is engaged.  On many receivers, there are selector stops on the left side of the receiver to prevent over-rotation, but on M16 receivers without selector stops, or if you put the selector lever on the right side where there are no selector stops, (such as ours, which is fully modular), an M16 selector will rotate 360 degrees.

Semi auto selector's detent holes will only allow you to rotate it between the detent holes, not beyond them.

Thus all semi auto selectors are not "milspec", they cannot be. 

There are no standard to speak of when it comes to specs for the semi auto detent hole, detent groove depth, shoulder depth, and groove angles.  There's also no written in stone specs we know of regarding the selector's bar / axis / center length.  Given that all receivers vary somewhat in width, this often becomes a problem.  A very thick receiver will find the selector lever binding on it, a very thin receiver will see pronounced gap between the receiver and levers.  We have spent countless hours and much of our resources to find a great combination, honestly nobody thought there was so much to a simple selector.

Pics:

From left to right: Battle Arms Dev. semi auto, cast, unknown brand M16 selector, and Battle Arms Dev. M16 (all Battle Arms selectors are CNC machined)

Special attention to the M16 selector detent holes and groove.  A milspec selector's detent holes will allow you to rotate it both ways.  On our current M16 selectors, this can't be done, though the first version of our M16 selector did use the milspec and could also be over-rotated.  In this case, the detent holes of a semi auto selector should not look like those on an M16 selector.

Top two are Battle Arms Dev. selectors, bottom is cast, unknown brand M16 selector

[img width=810 height=545]http://i75.photobucket.com/albums/i314/Duffypoo/selectorcomparison.jpg

Battle Arms Dev's redesigned detent hole depth and angle, groove depth and angle, and shoulder depth

[Oz]

Cool write up and some good and interesting points.

Yeah, my definition of mil-spec is; the most extreme tolerances the military will allow a contractor to meet to ensure that the component will still function.  Mil-Spec is by no means an endorsement for accuracy or well-fitting pieces.

And you're right about "Mil-Spec" not being possible in the part specifications itself in this case.  But you could say "meets or exceeds Mil-Spec tolerances".  That could be a true statement since the tolerances indicate the +/- variance dimensions.  Yes, misleading, but factually accurate and a way to have the words "Mil-Spec" associated with civilian (non-military) parts.

[Battle Arms Dev]

Right, one can exceed milspec in material and finish and not cause any problems.  Spikes NB coat some components, some manufacturers use Cerakote, Duracote, Melonite, all arguably better than Parkerizing.  Since the spec didn't call for anything else, these coatings exceed specs, but they're also not in specs  because they have varied from specs.  The parts that are of importance to us are tolerances.  Without these values, one has to reverse engineer the component using the numbers taken from a bunch of existing products, and hopefully come to an average that works.

In the case of the selector center, the areas that need to be changed are:

Detent holes (you can see the bi-directional detent hole I was talking about in the pictures)

The center's flat section (milspec would cause a few aftermarket triggers to fail, therefore for better compatibility, we reduced it, as almost every other selector maker)

Specs also change.  Vietnam era, and older M16 receivers are found to be rather thinner than current thickness, this causes excessive gap between the selector levers and the receiver.  Current specs are 0.878 to 0895, some old M16 receivers measure 0.74 and less.  So when one speaks of milspec, it covers a lot of area and length of time, time itself is a variable in this equation.