The AB Arms Mission Critical Kit is a collection of critical replacement parts for you and your AR-15/M-4 that are there to serve you in your time of need. The MCK is manufactured for military and law enforcement, as well as civilian firearms enthusiasts. The MCK will make sure you have what you need, when you need it.

The Mission Critical Kit includes the following items:

- 1 AB Arms Complete Nickel Boron Coated Bolt Assembly: The A*B Arms Nickel-Boron coated bolt assembly is a high-quality, Swiss machined replacement for your existing bolt should the cam pin hole or lug area crack
- 1 AB Arms Firing Pin: The A*B Arms chrome plated firing pin is used as a replacement for the bent or flattened firing pin tips
- 1 Firing Pin Retaining Pin: These are usually lost or damaged when replacing your bolt or by prying and pounding on it
- 1 AB Arms Extractor: Always good to have an A*B Arms, Swiss machined extractor available when your existing extractor tooth breaks
- 1 Extractor Axle: Replacement extractor axle in case it’s lost while cleaning your bolt
- 6 Gas Rings: Existing gas rings are usually bent or broken by slamming the bolt into the carrier when re-assembling the bolt group. We’ve got you covered twice on this one
- 1 Bolt Assembly Instruction Card: Never hurts to have an instruction card when you’re in a stressful situation
- 2 UV Resistant Black Gear Bands: These UV resistant gear bands will keep it all together when needed
- 1 AB Arms Latex Barrel Cover: Don’t let this part fool you. It will come in handy at one time or another
- 1 5.56 Broken Shell Extractor: Helps get those stubborn shell casings removed from your chamber at exactly the right time
- 2 Vials of 3ml Breakthrough Battle Born High-Purity Oil: We’ve included two convenient spray vials of this synthetic, non-toxic gun oil. Great for areas where friction and wear are expected
- 2 Latex-Free Adhesive Bandages and Alcohol Prep Pad: Great for those annoying cuts when you’re out in the thick of it.
- 1 Tactical Black, Ballistic Nylon Case with Multiple Gear Pockets: This 5”x 3.5”x 1” compact zippered pouch is an EDC style kit that’s small enough to fit into your pocket or gun bag