MD Enhanced Bolt Carrier Group in detail
This is an overview of the MD Enhanced Bolt Carrier Group. If you need an overview of how a BCG works Check out this article here
Precision grinding is a manufacturing process used in industries where tight tolerances are a requirement. Why this hasn’t been used in the firearms industry from the beginning I’m not really sure. Machines can only get so close to perfect when making parts and that is where precision grinding comes into play. This means we can create near identical BCGs part after part. This is great for even wear of the carrier that prevents uneven wear that causes malfunctions. Another thing this does is nearly guarantee that when you need to change your BCG out its going to be a perfect fit to your rifle. You won’t have different wear areas that will cause issues. Since we also do this inside and out it makes a perfect fit on the inside of your carrier, so you don’t have to deal with too tight of a fit for your bolt.
Armor Lube Coating
To further enhance the reliability of the rifle we use a coating called ArmorLube. It’s a type of advanced DLC like coating. It was developed with the army research center over the last 10 years. As of November 2022 it was written as the new Mil spec coating for the M4 BCG. In the latest taper linear abrasion testing it lasted 97,692 wear cycles. As a comparison the next closest coating was nitride and it lasted 28,625 wear cycles. On top of being extremely durable it has less than .1 friction coefficient. It’s very difficult for dirt or debris to attach to it and creates less heat in the internals from friction. Its corrosion resistance is also better than all of them as well.
9610 alloy is our material of choice. It is a very high strength metal that has a very high wear, corrosion, and heat resistance. It also is a very machinable metal that makes it easy to make precision parts. One bonus is if it’s properly heat treated it will have 7% more strength than Carpenter 158. There are a lot of heat treaters out there and very few do it the right way. We took a very long time to find a heat treater that put as much care into their work as we do. Statistic time. They heat treat 40,000 bolts a month and over the last 7 years have only had 4 go bad. That’s a great track record.
8620 is the metal of choice for the carrier here. I think this is a universal choice for 90% of the carriers out there. That’s because it has a great balance between strength and toughness which helps with repeated impacts from firing. It also has great case hardening properties. This is a surface hardening process that increases wear resistance on the outside while keeping the inside softer to prevent brittleness that too hard of metal has.
Chrome plating is one of the bests things you can do to a firing pin that will increase it longevity and reliability. This is an item on the BCG that takes a beating and needs to be tough but also has a smooth finish to operate reliably. If the firing pin is slowed down because of poor coating it will cause a lot of light primer strikes especially in hard primers. SP4 is another coating we are playing with that may create a much more even finish and have more wear resistance. Until we finish testing SP4, chrome is the best and we reserve the right to change our mind.
Gas rings are one of the highest friction items in a BCG and are critical to maintaining the gas seal inside the carrier. That seal is what produces reliable function. So why don’t other companies coat their gas rings at all and just leave them bare? I have no idea, but it does blow my mind how overlooked this is. Well we coat our rings in SP4. SP4 is a nitride coating that greatly increases the hardness of the rings and makes them significantly more resistant to heat. So, it protects them from heat and friction. Yes, we had the audacity to protect the gas rings from heat and friction.
Sealed and staked
So, staking is the process of crushing the gas key around the screws. Since this is a part that takes a beating from the gas return it just makes it that much harder for the screws to back out. I think the last test we did with the standard screws took it from 80 lbs of force to remove them without staking to 120 lbs to take the screws out with staking. We step it up though and use OCKs screw that are notched. So not only is the metal squeezing the screws it is getting interlocked with it. It doesn’t just make it hard for the screws to back out. It makes it impossible.
Sealing is something that most companies don’t do because it’s time consuming. Most shooters won’t be affected by the gas leakage that comes from not sealing a BCG, but we build ours as if it’s the last rifle you will ever have. It’s hard to guarantee something will be there for you when you need it unless you take the steps to ensure it. We use a thin sealant between the gas key and carrier to close it off and prevent any gas leakage between the two parts. Most gas keys leak that aren’t sealed if you’re wondering.
Alright well that was a lot of information. The key take away here is we put a lot of thought into how we build our rifles. There isn’t one part on the MD Enhanced Bolt Carrier group that we haven’t put thought into, and it shows with how reliable and durable these BCGs run. They don’t only run great in our rifles. They run great in other companies AR15s as well. That’s why they are released as a stand along product. Click here to check them out.