Mil spec vs Commercial
Living in CA, I decided it would be easier to get a couple of lowers and build and switch uppers depending on what I was planning on doing.
What was the purpose of commercial spec AR's? Most AR's on the market seem to be mil-spec, but seems there are many parts that are listed as commercial spec.
What was the purpose of commercial spec AR's? Most AR's on the market seem to be mil-spec, but seems there are many parts that are listed as commercial spec.
0
-
Mil-spec vs commercial only applies to the collapsible stock dimensions. The buffer tube outer and extendable stock inner diameters are larger on commercial than on mil-spec. Someone else can likely quote a reason for this. No big mind bending conundrum-just stick with one or the other.
All other parts within the lower are basically same specifications.0 -
Basically, the milspec extension has a stepped up area where the threads are cut, which gives a uniform wall thickness where it attaches to the receiver. As a cost cutting measure commercial tubes are straight walled and have the threads cut down into the tube, resulting in thinner walls. The effect of this is creating a shear point where it attaches. This might be of no consequence to the casual range shooter, but a receiver extension more likely to break when it receives a hard blow is unacceptable on a military weapon. 
When building an AR using components obtained from multiple sources you need to keep in mind is that the term 'milspec' is VERY loosely applied by AR and component amanufacturers. For example, it's common that even when only an aspect or two of a complete rifle actually conforms to military specifications it's commonly marketed as a milspec gun. Aftermarket receivers stating they're milspec based simply upon receiver extension measurements are an example.
In truth that term refers to an item which is produced in full compliance with what's referred to as a DoD Technical Data Package (TDP). This contains all aspects of the item's manufacture, from the quality of raw materials all the way to endurance testing of the final product.
After a piece of equipment has passed all military acceptance protocols the TDP describing it's manufacturing standards/processes is accepted and all phases of it's production are then monitored by DoD personnel to insure that it continues to be produced in strict compliance with this very detailed document.
To give you an idea of just how detailed we're talking about here, the printed TDP for an M4 would just about fill an entire pickup bed.
Many don't realize that this full TDP for the M16 family of US military weapons is a proprietary item which is only available to Colt and FN, which is not allowed to sell their rifles on the commercial market. In short, Colt is the only AR available that can possibly by true milspec.
In addition to DoD personnel stationed at their factories and physically monitoring each phase, several times per month completed rifles coming off Colt and FN's production lines are randomly pulled and fully tested for compliance. This practice also insures a Colt commercial buyer he's getting a high degree of quality consistency.
What all of this boils down to is that a non-Colt or FN 'milspec receiver' cannnot be guaranteed to be of the same quality of raw material, all of it's measurements may not be precisely the same, it's finish may be look the same but actually be different, changes in any of these may occur from time to time, etc.
A handful of non-Colt/FN AR manufacturers do produce a very good product, but the rule when dealing with them is let the buyer beware. The devil is in the details and there are a LOT of them.0 -
Thank you for such a complete answer, that was quite an education.
I have a couple of S&W lowers I'm building on and an LWRC and wanted to acquire and upgrade stocks and ran into the military/commercial issue.0
Please sign in to leave a comment.
Comments
3 comments