Issue link: https://let.epubxp.com/i/303456
31 www.officer.com May 2014 Law Enforcement Technology FIREARMS TACTICS expected to perform hot, cold, wet or dry. Not every user will clean and inspect after a shift—although this is good prac- tice. On my car-mounted shotgun most of the wear on the finish was from trans- porting, not shooting. The MMC Tactical Upper Receiver C14.7 is a conventional direct gas impingement upper. They make a longer one, but I like 14.7. Its barrel is profiled for heat dissipation and it weighs about six pounds. Attached to my Del-Ton receiver its balance is slightly forward, for a smooth transition on multiple targets. Now, I get to shoot a lot of guns. I test a lot of gun components. I know it's a dream job, but I do the same things our readers do. They all run together, unless something is outstanding. I found the MMC upper is unforgettable not just in quality, but in accuracy and handling. Besides its great handling, it is a collec- tion of the best features to install in an upper, period. The Upper Receiver C14.7 is machined from 7075 T6 alloy with a smooth finish and consistently applied hard coat anodization. It has M4 feed ramp cuts, and the barrel extension has M4 feed ramps. M4 feed ramps are additional relief cuts where the cartridge feeds into the chamber and the barrel extension. There is some debate about whether they provide any kind of advan- tage. Will my gun run without them or is my reliability improved with them? The answers range from "can't live without them" to "really makes no difference." I find that they allow for more margin of error in feed angle, which could compen- sate for a less-than-ideal feed lip, so I rec- ommend them. The ramps in my MMC C14.7 are smooth and continuous. My C14.7 fed anything I gave it. I used several different brands of ammo and never experienced any problems with operation. The entire bolt assembly is nickel boron coated. This gives it a more durable and harder finish than the bolt material. Nickel boron coating is a process where a hard surface is plated on the metal surface. The plating forms round tipped microscopic nodes on the surface of the metal. Besides mak- ing the gun part look great, this feature reduces the metal-to-metal surface contact. Because it creates hills and valleys of the nodes in the metal sur- face, the metal dissipates heat better. Theoretically the parts can run together without lubricant (though I'm not test- ing this aspect) I always recommend lubricant. It does have a slicker feel than standard parts, and metal-to-metal sur- faces definitely run better. The bolt assembly's bright finish exposes carbon buildup, making inspec- tion and cleaning easier. As a law enforce- ment armorer, I had an inspection sched- ule for all service firearms. This finish Above: an MMC Armory nickel boron coated bolt assembly. Not only does it look great, we actually had a look at the surfaces under a microscope, which easily explained why it ran so well. It has a naturally smoother surface. After enough rounds down range, it also proved easier to keep clean. This translates to longer component life and increased reliability. For me, the AR-15 is a perfect "traffc stop gone bad" tool, where the rife may engage a barricaded suspect. DTTactical Ammunition from DoubleTap Ammunition performed well in our MMC Upper, especially past 50 yards. We used a couple of different cartridges from this company. Their ammunition is particularly clean burning. The 55gr FMJBT round will feed reliability and give a great performance in almost any duty AR-15. This is a 2,950 fps, 1,200 FPE cartridge. LET_30-33_FirearmsTactics0514.indd 31 4/18/14 3:29 PM