CMMG Mk57 5.7X28mm Firing Pin Kit Review

First Impressions of CMMG Mk57 5.7X28mm Firing Pin Kit

The CMMG Mk57 5.7X28mm Firing Pin Kit is a crucial component for anyone relying on the CMMG Mk57 platform. This isn’t a flashy accessory, but a vital maintenance or repair item designed to keep your firearm running smoothly. It addresses a common concern: the eventual wear and tear of critical internal parts.

I needed this kit because I’ve put thousands of rounds through my Mk57 upper receiver on my AR-15 pistol. After a recent string of light strikes, I suspected the firing pin was nearing the end of its service life. A reliable firing pin is the heart of any firearm’s ignition system, and peace of mind is paramount, especially when using a less common caliber like 5.7x28mm.

Upon receiving the kit, my first impression was one of solid, no-nonsense construction. The firing pin appeared to be machined from quality steel, exhibiting a clean, consistent finish. The included retaining pin also looked robust, certainly an upgrade over a potentially fatigued original. This is a direct replacement part, so I wasn’t expecting anything groundbreaking in terms of design, but the visible quality inspired confidence.

I considered a few aftermarket firing pins, but ultimately chose the CMMG kit for its guaranteed compatibility and reputation for reliability. Some generic kits might save you a few bucks, but firearm parts are not the area to cut corners. My initial feeling was positive – a well-made, essential part that promises to restore my Mk57 to its peak performance.

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Real-World Testing: Putting CMMG Mk57 5.7X28mm Firing Pin Kit to the Test

First Use Experience

I installed the CMMG Mk57 5.7X28mm Firing Pin Kit the day it arrived and headed straight to my local outdoor range. It was a relatively mild day, around 65 degrees Fahrenheit with a slight breeze. I brought along several hundred rounds of various 5.7x28mm ammunition, including Federal American Eagle, FN SS197SR, and some handloads I had been testing.

Installation was straightforward, thanks to CMMG’s commitment to Mil-Spec dimensions. The new firing pin and retaining pin dropped right into the Mk57 bolt carrier group without any modification or fitting required. After the install, the Mk57 upper was placed on my AR-15 pistol lower. My first magazine of Federal American Eagle ran flawlessly with zero light strikes. This was a great sign considering the light strikes that had been occurring previously with the worn firing pin.

Extended Use & Reliability

After several months of use, I’ve put approximately 2,000 rounds through my Mk57 upper receiver with the CMMG Mk57 5.7X28mm Firing Pin Kit installed. It continues to perform flawlessly. I have not experienced a single light strike or any other firing-related malfunctions.

The firing pin shows no visible signs of wear, despite the relatively high round count. Cleaning is simple; I typically wipe it down with a CLP after each range session and apply a light coat of oil. Compared to the worn firing pin I replaced, the CMMG kit provides a significant improvement in reliability and peace of mind. The original firing pin had flattened slightly at the tip, likely due to excessive use.

Breaking Down the Features of CMMG Mk57 5.7X28mm Firing Pin Kit

Specifications

The CMMG Mk57 5.7X28mm Firing Pin Kit includes two essential components: a firing pin and a retaining pin. Both are manufactured to strict CMMG specifications. The firing pin is made from heat-treated steel, ensuring optimal hardness and resistance to wear.

• Caliber: Specifically designed for the 5.7x28mm cartridge. This ensures proper primer ignition and reliable function.
• Material: Constructed from high-quality steel for durability and longevity. The heat-treated steel resists deformation and breakage under the constant stress of firing.
• Compatibility: Exclusively for the CMMG Mk57 bolt assembly. This ensures a perfect fit and reliable operation within the intended system.

Performance & Functionality

The CMMG Mk57 5.7X28mm Firing Pin Kit delivers consistent and reliable ignition of 5.7x28mm ammunition. The firing pin’s precise dimensions and hardened steel construction ensure a strong, consistent strike on the primer. This eliminates light strikes and misfires, which can be a common issue with worn or out-of-spec firing pins.

The kit’s performance is a significant upgrade over a worn or damaged firing pin. This is essential for maintaining the reliability and functionality of your CMMG Mk57 firearm. It exceeded my expectations because the 5.7x28mm is a bottlenecked cartridge. That requires a firing pin to function correctly due to headspace and primer depth issues.

Design & Ergonomics

The CMMG Mk57 5.7X28mm Firing Pin Kit is designed as a direct replacement part. It mirrors the dimensions and geometry of the original firing pin. This ensures a seamless fit and function within the Mk57 bolt assembly.

The kit is incredibly user-friendly. Installation requires only basic tools and knowledge of AR-15/Mk57 disassembly procedures. There is virtually no learning curve involved, making it accessible to most firearm owners.

Durability & Maintenance

The high-quality steel construction of the CMMG Mk57 5.7X28mm Firing Pin Kit ensures excellent durability. It should withstand thousands of rounds with proper maintenance. Regular cleaning and lubrication will extend its service life even further.

The firing pin is easy to maintain. Simply wipe it down with a CLP (Clean, Lubricate, Protect) after each range session to remove carbon buildup and prevent corrosion. A light coat of oil will keep it running smoothly.

Accessories and Customization Options

The CMMG Mk57 5.7X28mm Firing Pin Kit is a direct replacement part, and therefore does not offer significant customization options. It’s designed to work seamlessly with the CMMG Mk57 bolt assembly as-is. However, some users might consider aftermarket coatings to further enhance corrosion resistance or reduce friction.

The kit is compatible with any standard AR-15 armorer’s tools required for bolt disassembly and reassembly. This makes installation and maintenance convenient for owners of AR-platform firearms.

Pros and Cons of CMMG Mk57 5.7X28mm Firing Pin Kit

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Who Should Buy CMMG Mk57 5.7X28mm Firing Pin Kit?

The CMMG Mk57 5.7X28mm Firing Pin Kit is perfect for owners of CMMG Mk57 firearms who want to ensure reliable performance and maintain their firearm’s functionality. It is also a must-have for anyone who shoots their Mk57 frequently or uses it for self-defense. The kit provides peace of mind and prevents potential malfunctions.

This product might not be necessary for those who rarely shoot their Mk57 or have a relatively low round count. However, even occasional shooters should consider keeping a spare kit on hand for preventative maintenance. No must-have accessories or modifications come to mind outside of maybe a good armorer’s tool kit.

Conclusion on CMMG Mk57 5.7X28mm Firing Pin Kit

The CMMG Mk57 5.7X28mm Firing Pin Kit is an essential component for maintaining the reliability and performance of any CMMG Mk57 firearm. The high-quality construction, guaranteed compatibility, and ease of installation make it a worthwhile investment.

The price of $23.43 is justified by the peace of mind and increased reliability it provides. You can rest easy knowing you have a functional firing pin. I would personally recommend this kit to any CMMG Mk57 owner who wants to ensure their firearm is always ready for action.

Don’t wait until your firing pin fails. Invest in a CMMG Mk57 5.7X28mm Firing Pin Kit today and keep your Mk57 running smoothly.