Para Bellum Arms Enhanced AR-15 Bolt Carrier Groups
Manganese Phosphate
While our Enhanced Mil-Spec BCG shares the same finishes as a Mil-Spec BCG, it is so much more. Enhancements include:
- Michiguns O.C.K.S.
- Sprinco Gas Rings
- Sprinco Ejector Spring
- Sprinco 5-coil Extractor Spring
- Sprinco Viton O-ring
Hard Chrome
Our Enhanced Chrome BCG shares the same core features as the base model, but with an upgrade to a hard chrome finish for the bolt head, bolt carrier, and cam pin. This finish offers improved durability and lubricity.
Diamond-Like Carbon
Our Enhanced DLC BCG shares the same core features as the base model, but with an upgrade to a diamond-like carbon finish for the bolt head, bolt carrier, gas key, and cam pin. This finish offers ultimate durability and lubricity.
Meet the PBA Enhanced BCG Family
The bolt carrier group is the heart of the AR weapon system. Arguably, it is the most important moving part of the gun. Because of this, we spent a little extra time and effort searching for the right BCGs for our guns.
Our Enhanced AR-15 BCGs are purpose built from the ground up to ensure absolute reliability and top-level performance. The story of how we got there is one of stubborn determination and uncompromising expectations. And it almost didn’t happen (several times). In the end, we are very please with how it turned out.
We like to know everything about everything in our guns. We are weird like that.
We want you to know everything about everything in our guns. We are transparent like that.
For our BCGs, we wanted to make sure that every part was fit for purpose. Each sub-component experiences different conditions/stresses and not every material or finish is best for every condition/stress. So, we agonized over the materials and finishes for each sub-component. Where there were differences of opinion, we went to the industry experts for their take.
Below, you will find the final specs of each sub-component in our BCGs. Below that, you will find some of the highlights of our BCGs. If you still have questions about our BCGs, just ask.
We Inspect/Gauge the Crap Out of Every BCG
Every BCG Test Fired
We have a lot of faith in our BCGs, before they even end up in a gun. Microbest, Sprinco, and Michiguns make phenomenal quality components. We gauge critical components when they arrive. And everything is assembled properly. However, we like to have the highest degree of confidence in our products. So, we live fire test every single BCG. We will never ship a product that doesn’t work, because every single product needs to work before we ship it.
Please note this means that every BCG could show corresponding signs of use. Rest assured: if it is sealed in the package, it has only been fired by Microbest (for HPT) and Para Bellum Arms (for BCG and Upper Receiver Assembly QC, as applicable).
Permatex Aviation Gasket
Microbest manufactures to phenomenal tolerances, to the point that their BCGs don’t actually need gas key sealant. We still have them use Permatex to seal the gas key to the carrier. It is the Mil-Spec and it provides an added level of assurance that your gas system is sealed and efficient. It is worth noting that most consumer manufacturers don’t seal their gas keys.
Michiguns O.C.K.S.
Gas key screws have a very important job and are subject to extreme stresses. While grade 8 gas key screws are good enough for the Military, we went out of our way to use Michiguns’ Optimized Carrier Key Screws (O.C.K.S.) in all of our builds. The full height knurling and crown notches deliver bombproof security of the gas key when properly staked, as of course ours are.
Sprinco Springs
Standard extractor and ejector springs are fine. But they are not good enough for us. We put Sprinco 5-coil extractor springs and Sprinco ejector springs in all of our builds for ultimate reliability. Sprinco chrome silicon spring wire is heat treated (for strength), stress relieved (for reliability), cryogenically processed post-winding (for longevity), and impregnated with a micronized molybdenum disulfide compound (for lubricity). That may seem like a lot of effort for a tiny spring, but the result is a more consistent, more reliable, and longer-lasting spring and bolt assembly.
We also pair the Sprinco 5-coil ejector springs with Sprinco CRANE Viton O-rings, because that is what the experts at Sprinco have advised us to do. Per their guidance, while you should use both the O-ring and the insert for a standard extractor spring, you want either the O-ring or the insert with the 5-coil springs (you can use both, but installation would be a bitch). Most other companies pair the 5-coil extractor spring with the insert, instead of the O-ring. We asked Sprinco for their advice, instead of blindly following the trend. The advice we received was observational, based on real life experience with the 5-coil spring, and was contrary to common practice: Sprinco advised us that, while the O-ring will have the same effect as the insert on function of the extractor spring, the O-ring/5-coil combination will far outlive the insert/5-coil combination (they have documented evidence of several hundred thousand rounds through an O-ring/5-coil combination without signs of wear or degradation).
Note that while the 5-coil extractor springs will work extra hard to tear a stubborn spent case out of the chamber, they may not be kind to your brass. If you reload, this may be a problem for you. That is why we include a standard 4-coil extractor spring and the recommended extractor insert with each BCG, just in case you want to swap it out for a gentler (albeit less persuasive) alternative.
Sprinco Gas Rings
As a consumable component, standard gas rings are fine. But we wanted more. Again, we turned to Sprinco’s superb quality for gas rings. And the market tells us that their cryogenically processed gas rings last much longer than standard rings. In pursuit of ultimate quality, reliability, and longevity, we insisted on Sprinco gas rings.
Nitride? No thank you.
Finally, we want to acknowledge a specific finish that we did NOT use in any of our BCGs, just so you understand that it was a conscious choice. We knew, out of the gate, that we didn’t want nitride in our BCGs, by any name (salt bath, FNC, QPQ, melonite, etc.). We will not get into all of the technical details here (there are so many reasons), but suffice to say that nitride is not the best finish for the BCG.
Most importantly, nitride is not an appropriate finish for the bolt. Check out our Don’t Buy a Nitride Bolt article for details.
There are better finishes for the carrier. A nitride carrier is nitride, inside and out. We have no issue with nitride (especially QPQ) on the outside of the carrier. Our biggest gripe with nitride carriers is that nitride is used in place of the hard chrome lining of the carrier. Why is that important?
For the manufacturer, nitride is cheaper and faster. But that doesn’t benefit you (especially since you’ll probably pay more for a nitride BCG than a chrome-lined phosphate BCG).
Hard chrome is the Mil-Spec finish for the bore of the carrier and the lining of the gas key. The Mil-Spec calls for hard chrome for good reason. The carrier and gas key see a lot of abuse: scorching hot gas, high pressures, the friction of metal-on-metal, the impact of the gas key on the gas tube.
Hard chrome is an electroplated finish that is deposited on the surface of the metal. Is is very hard and durable, and (importantly) is temperature stable.
Conversely, the nitride finish softens and begins to degrade/diffuse above 900° Fahrenheit. This is a relatively low temperature for the path of hot gas in an AR. While most shooters won’t shoot enough to get the BCG hot enough to soften the nitride, we don’t like the limitation (we don’t want to apply the disclaimer “not suitable for sustained or full auto fire” on our BCGs).
In summary, we refused to compromise the durability and longevity of our BCGs with nitride, just because it is cheap and looks nice. Nitride may find a good home in some places on the AR; but our BCG is not one of them.