Description
The requirements for assembly of our Bolt Carrier Groups are much higher than most. Before assembling the gas key to the carrier, permatex NO.3D aviation is applied to form-a-gasket around the gas hole (per MIL-SPEC). Then Grade-8 hardware is used to attach the gas key, followed by properly staking per spec. When installing the extractor to the bolt, a crane-o-ring is inserted with the spring to insure proper ejection. Then high temperature grease is applied to the gas rings before inserting the bolt into the carrier, which allows for much smoother operation. These BCGs are inspected to the highest of standards, to insure a high quality product that is 100% reliable for our customer… PROUDLY MADE IN THE USA!
Carrier
UCT Coatings EXO Technology Nickel Boron Treated
M16 style (Auto)
Machined from 8620 tool steel
Heat treated to military specifications
Bolt
Black Nitrided
Machined from 9310 tool steel
Heat treated to military specifications
Shot Peened
Ground to meet military required tolerances
MPI (Mag Particle Inspected)
Gas Key
Black Nitrided
Machined from 4140
Heat treated to military specifications
Extractor
Black Nitrided
Machined from 4140
Heat treated to military specifications
Shot peened
Firing Pin
Machined from 8640 tool steel
Heat treated to military specifications
Ground to meet military required tolerances
Coated with .0002”-.0003” of hard chrome per MIL-STD-171 1.2.2.2
Cam Pin
Black Nitrided
Machined from 4340
Quench and temper heat treat
Ground to meet military required tolerances
SKU: XAIMBCGX
Comments (5)
Sigh. I knew they were hiding the nitrided bolts somewhere. Dammit, AIM, I need a few of your nitrided bolts and you've not been selling them stand-alone for a while. rrr.
rr.
r.
How do these compare to the regular nickel boron ones?
By the science, there is an argument that these are better.
For example, nickel boron is the coating that mostly benefits the cleaning process. You want the carrier in a DI system to be easy to clean. There maybe some surface hardening over park'ed steel, but that is not the design intent. There is also a lubricity component in NiB that people value.
Nitride is a whole different ball of wax. Here are the main characteristics (lifted from the website of a materials supply company I'm familiar with:
* Excellent wear resistance/hardness
* Low thermal expansion
* Good chemical corrosion resistance
* High temperature performance
* Good thermal shock behaviour
* Good flexural strength
* Low weight
* High Stiffness
* Electrically insulating
The idea is that the nitride bolt (where you want parts the strongest) uses this treatment to improve its strength, wear characteristics, things mentioned above, etc.
Probably just cheaper for AIM to put the melonite bolt and key on an already exo carrier . Not really any advantage to having only those parts nitrided as far as I know.
Nothing wrong with Nitride or Nickel Boron coatings. They each provide benefits. if I wasn't just taking a quick break from a project I would take the time to post a couple substantive links. Search for yourself or take my word as one who has extensive experience with various coatings in firearms applications.
Nickel Boron coating provides a higher degree of lubricity (friction reduction) than Nitride treatments. The result is Nickel Boron will typically be smoother and easier to clean than Nitride treated surfaces.
Nitride treatment has greater resistance to wear under extreme temperature than Nickel Boron coatings.
Essentially, in the long term, after many thousand rounds, a nitrided bolt carrier group will show less signs of significant wear than a Nickel Boron carrier group.
In the short term, the nickel boron will clean easier and feel smoother to the touch.
Other factors when selecting a bolt carrier which to me are of even greater importance then the type of coating or treatment is the material used, as well as the final machining or surface prep done prior to coating or treatment. In no way are all Nickel Boron bolt carriers equal. Some begin with a relatively rough surface and rough final machining and then go straight to coating. The coating does not significantly change the surface contour. On a slightly magnified level, the coated surface will look more like a golf ball than a smooth surface. In contrast, other carriers which are smoothly machined and have the surfaces polished will look drastically better even to the naked eye.
the same is true for nitride treatment with or without the surfaces being prepped or polished. A perfect example is the JP enterprises enhanced bolt carrier with the nitride finish. The polished carrier, is easier to clean than a Nickel Boron coating on an unpolished carrier. Even though the lubricity of Nickel Boron can be made to exceed that of nitride, if the surface is not properly prepped you will not get full benefit. There are also examples of finely polished Nickel Boron units such as the Kies Bolt Carrier or the superior JP enhanced bolt.
Regardless of all of the options, the truth is that most people never fire enough rounds to wear out there carrier. Secondly, it is intended to be a replaceable part, not a "last forever" item