APF SP4-coated BCGs Machined to Military Specifications & Made in the USA

Alex Pro Firearms (APF) is proud to introduce BCGs featuring SP4 a hybrid DLC (Diamond Like Carbon) coating that is the result of over a year in development. SP4 combines high hardness (2500-3500 HV) with ductility to remain tough without exhibiting brittleness vs common PVD/DLC type thin film coatings. SP4 reduces friction and improves wear resistance for metal components which provides a longer life span and requires minimal maintenance with little to no lubrication. It has been tested to -44F in the mountains of Alaska and has been tested in both Iraq and Afghanistan with no lubrication which is a huge advantage in desert environments and extreme cold. SP4 has passed the ASTM 85 (Annex 1) Salt Fog test and provides the best hardness/lowest friction co-efficient while maintaining the ability to “move” with the metal it is protecting. Includes a hand polished bolt carrier with a chrome lined bore and staked gas key bolt with gas rings firing pin cam pin and firing pin retaining pin.
Longer Product Lifespan (BCG) High Hardness High Wear Resistance Extremely High Lubricity

BOLT: Carptener 158 Shot Peened Heat Treated SP4 Coating
CARRIER: SAE 8620 Heat Treated SP4 Coating Full Auto
EXTRACTOR: CNC machined Shot Peened Heat Treated SP4 Coating
FIRING PIN: Swiss machined Heat Treated Precision ground SP4 Coating
GAS KEY: CNC machined Heat Treated Chrome Lined Torqued and Staked to Carrier Mil Spec. SP4 Coating
CAM PIN: Swiss machined Heat Treated SP4 Coating