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 ground
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.
Bolt material
Carpenter 158 is used in our bolts for our bolt carrier groups (BCGs) because it offers exceptional strength and durability. This high-performance alloy steel is known for its ability to withstand extreme conditions, including high temperatures and significant mechanical stress. Its superior wear resistance and fatigue strength ensure that the bolts maintain their integrity over time, even under heavy use. Additionally, Carpenter 158 has excellent machinability, which allows for precise manufacturing and tight tolerances, ensuring that the bolts fit perfectly and function reliably. This material choice enhances the overall performance and longevity of the BCG, making it a critical component in high-performance firearms.
Carrier material
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.
Firing pin
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
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.
Overview
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.
