Faxon's 9mm BCG is not compatible with the Spike's Tactical Colt 9mm Lower Receiver.
The AR platform has lent itself to all manner of variations. Longevity and standardization of the brand have enabled shooters to mix and match their way to just about any goal. However, when it comes to an AR configured in the pistol caliber blowback design, this luxury becomes limited. You have to choose parts that are going to play well together. Otherwise, you may be disappointed with your results. The 9mm BCG is one of those parts that can make or break a build.
The Faxon 9mm bolt carrier group comes in the M16 style. This means it's rated for full-auto and it is considered a full-mass component. This designation is particularly important in a 9mm blowback style weapon. This design relies on a heavy buffer, buffer spring, and the weight of the BCG to keep its action closed. The weapon's action isn't physically locked shut before firing. Instead, the system is inertia based.
A history of powder and carbon fouling plague the popular 9mm cartridge. The hardened, nitride finish of the Faxon 9mm bolt carrier group is a perfect shield against this problem. Once the fun is done, cleaning your gun isn't such a chore. Additionally, Faxon Firearms made some improvements over its 1st gen BCG that are not so obvious. Faxon replaced a problematic internal extractor with an external AR-15 style extractor. This change increases the reliability of your gun by reducing the chance of an FTE. They also went to a stronger firing pin inside their 9mm BCG. Again, Faxon is working to give you a more reliable weapon. This is next generation engineering at yesterday’s price.