Mil Spec sounds like it's Military tough, but what does it mean to be Mil Spec vs Commercial Spec? Well, if you don't mind if I spoil it for you, you're really shooting pretty much the same bullet from the same gun at the same speeds. So, not much in a practical sense. But, there are differences right? Yes, there are. In fact, there is a clear winner between the two.
So, what is Mil Spec? Well, this is a designation for a gun or part that is designed to be used on a military rifle with the tolerances, connection types, and materials specified by the Technical Data Package (TDP) and military manual of arms for the weapon. Generally speaking, these are chambered in 5.56, have chrome-lined barrels, use a particular set of dimensions, use particular materials (such as Carpenter 158 steel for the bolt), and use a specific anodizing process for finishing. Many manufactures make parts that are compatible with Mil Spec rifles, but are not truly Mil Spec. Truthfully, all ARs currently available are not actually true Mil Spec - many are based on Mil Specs. If you don't have certain features like select fire, a 14.5" barrel like an M4, or a solid A2 stock like an M16, then you don't have a M4 or M16, which is what the US military issues. The important thing to know about Mil Spec is that it's a huge part of the market - as in people are obsessed with Mil Spec rifles because they want to own something that is as close to what our military uses as is possible in the civilian world. Hence, people want Colts - not because they're the best ARs, but because of the idea that, "If it's good enough for our soldiers, then it's good enough for me." I understand that sentiment. If you think about it, Colt ARs are a great baseline for what your expectations should be for your rifle because they are a manufacturer of combat proven rifles and the civilian versions they produce use mostly the same parts. As a result of people looking for military weapons to ensure they are getting something they can "bet their life on," there is a huge market for Mil Spec-compatible parts.
For you and I, it's these Mil Spec-compatible parts that we should be most interested in. For instance, BCM doesn't actually make the M4A1 for the US Marines, but I wouldn't hesitate to use a BCM over the standard issue M4A1. (On a side note, full auto is not especially important to me because it really just wastes ammo faster. At 50+ yards, I really want to fire semi-auto exclusively, for accuracy.) The fact is, the Military makes decisions about their guns based partly on cost - literally weighing the value of our soldiers lives against the perceived benefits of any different or "new and improved" design. We have to make that choice too, but we get to make those choices for ourselves, unlike our soldiers. That is where the benefits of the civilian market come into play. You see, we can get parts that are better than Mil Spec. For instance, CHF Barrels or stronger, lighter, and snag-free stocks are benefits that our soldiers don't get because the military either doesn't see the benefit of these products yet or lacks the funding to swap out those parts for every gun in inventory. We also get to to choose what works best for us - "Does this stock fit the pocket in my arm well?" or "Do I want an 18" barrel for extra muzzle energy and better distance shooting?" or "Can I get a barrel with .223 Wylde chamber for better accuracy?" The thing to remember here is that we have a standardized set of specifications, Mil Specs, that allow us to swap out interchangeable parts on our rifles to custom fit the gun to our needs/preferences and, ultimately, make lighter, stronger, better rifles.
Ok, so how does all that relate to Commercial Spec, you ask? Commercial Spec is really just a different set of specifications than Mil Spec. The only differences between Mil Spec and Commercial that are worth noting are:
- The buffer tubes are different diameter and have slightly different threading. ( vs Mil:
- Commercial Spec generally isn't as demanding about specific materials.
- Commercial Spec rifles more commonly use .223 or .223 Wylde chambers for accuracy and sporting use. (Though, there is nothing that prevents you from putting a .223 barrel on a Mil Spec rifle - it's just not Mil Spec.)
So, which is better? For me, the answer is obvious: Mil Spec. I can already hear the cries from Bushmaster owners everywhere: "But, you just said the quality depends on the manufacturer, not the buffer tube diameter!" Yes, I did... and that is true, by the way. The reason Mil Spec is so clearly better is the number of available options. For instance, you won't find a Commercial Spec BCM Gunfighter stock - BCM doesn't make a Commercial Spec version. Because of the driving market force I described above (people wanting to get Mil Spec rifles that they can bet their life on) combined with a little hero-worship of our armed forces, there are just a lot more options if you go Mil Spec because it's more popular. That's how Capitalism works - companies produce more of what people buy more. The beauty of it is that you don't lose access to better than Mil Spec materials for your rifle by going Mil Spec - you just get parts that are meant to fit a Mil Spec rifle with whatever material you prefer. On the other side, you'll see that you have less options in terms of materials or designs for Commercial Spec because those rifles aren't as popular and, in some cases, proprietary. Ultimately, for customization and availability of replacement parts, the choice is clear: choose Mil Spec.