MR556 Bolt Carrier Conversion to HK 416C PDW
The Hk 416C is often referred to as an Ultra Compact Assault Rifle.
To make the firearm as compact and light as possible modifications had to be made to both the external parts such as the stock as well as internal pieces like the bolt carrier.
The stock made by Troy Industries uses a proprietary AR bolt carrier and since Hk has their own bolt carrier design for their gas piston upper, modifications have to be made to the Hk carrier to get it to work with the Troy Industries PDW stock.
The modification consists of machining the carrier to a shorter length and adding a custom made rear section to mate up with the PDW stock.
This modification also changes the carrier to the auto carrier specs by moving the sear trip lever area of the carrier forward to the 416 location for those that might want to use their PDW upper with a registered lower.
The rear of the carrier uses a standard AR buffer so there will never be a need to track down a proprietary buffer. The area forward of the buffer is also hollow so that additional weight can be added with tungsten etc to tune rate of fire or recoil.
The cost for the modification is $395. That includes converting the carrier to auto specs, machining/installing the rear section with buffer for the PDW stock, and parkerized finish. Nitride finish is available for an additional $45
Modified MR556 Carrier on Top Compared to Troy Industries Carrier Below