Unless you’re looking at some sort of special AR build kit, chances are that the BCG (bolt carrier group) it comes with is a mil-spec BCG – if it comes with one at all.
Since the BCG is basically the beating heart of your rifle, that along with the gas system and buffer tube system is responsible for cycling the action, it’s worth asking the question:
“Is a mil-spec BCG good enough for this AR build kit?”
Maybe, and maybe not. This post will break down some of the details.
What’s Good About Mil Spec BCGs
Just to keep things above board, a mil-spec bolt carrier group is going to have a hard black phosphate finish.
This is desirable for a few reasons. One is that it is a highly durable finish that is wear-resistant. The other is that it is non-reflective.
Also, since it is a standard, it is somewhat affordable. With that said, there are definitely some complaints that some shooters and builders have raised against it.
What’s Not So Good
First, the mil-spec phosphate coating is not as wear-resistant as some other finishes, like nitride. Anywhere the phosphate coating wears away, the BCG underneath will also be prone to corrosion.
Secondly, the phosphate coating has a fairly coarse tooth, which necessitates a greater degree of liquid lubrication. This, however, is a catch-22 because the more liquid lubricant is needed, the more debris will be trapped and the faster the finish will wear.
What Sorts of Upgrades Are Available
Now that we’ve covered the benefits and drawbacks of mil-spec bolt carrier groups, here are a few alternative options at your disposal:
- Black nitride
Black nitride is an electrochemical finish that is very hard and very thin, and which basically looks like a shiny black polish. Black nitride is hard, wear resistant, and exhibits excellent permanent dry lubricity, which means that less liquid lubricant is needed with it.
- Titanium nitride
Titanium nitride offers all of the benefits of black nitride, including the permanent dry lubricity that means that less liquid lubricant needs to be used with it. The difference is that it is more expensive, but it also sports an attractive gold-tone finish that some shooters find very appealing.
- Nickel boron
Nickel boron is an expensive bolt carrier group coating that more or less offers all of the benefits of titanium and black nitride, down to the permanent dry lubricity. Like other advanced bolt carrier group coatings, however, it can be quite expensive.
- Diamond-like carbon (DLC)
Diamond-like carbon, also known as DLC, is basically a very thin layer of carbon that insulates and protects the bolt carrier group. Like the other finishes mentioned here, it offers high wear and corrosion resistance as well as high permanent dry lubricity, but it is fairly expensive.
- Hard chrome
Hard chrome plate is another finish that was once more popular on AR-15 rifles than it is today. It results in a bright, shiny, silver-tone BCG that offers high wear and corrosion resistance, with less tooth than phosphate but less permanent dry lubricity than nickel boron, nitride, and DLC finishes.
Where to Explore AR Build Kits
If you’re here to learn more about AR build kits, or want to see what sorts of options are at your disposal, make your first visit to MCS Gearup.
They carry a wide range of AR build kits along with parts for upgrades so you can customize your build along the way.
In their collection of build kits and parts, they carry short buffer kits, short uppers for building AR15 pistols and short-barreled rifles (SBRs). For more information on what sorts of options you have, visit their website or get in touch with them at Sales@MCSGearup.com.
