7.62mm ABC/R v3 is incompatible with 5.56mm spec AR lower receivers.ABC/R has finally made its way to 7.62mm, LR308 pattern ARs. ABC/R v3 has incorporated refinements and lessons learned since the ABC/R (v1, 5.56mm) was introduced in early 2015 and v2 (2017 to 2020).ABC/R version 3 differs from v2 in the paddles design. V3 features a ledge on top of the upper paddle, and bottom of the lower paddle for increased traction. Due to the non-standard based nature of 7.62mm AR platform, many of 5.56mm ABC/R v3's features would introduce incompatibility issues on 7.62mm ARs.Please note that though the ABC/R v3's upper paddle is angled and tapered, and we have tested it on upper receivers with a small, oval shaped bolt catch paddle cutout, such as found on DMPS's LR308 upper receiver, the upper corners of ABC/R v3 7.62mm may come in contact with receivers and mar it in two small places inside the cutout.These are cosmetic only, they don't affect the functionality of the bolt catch. For receivers with a generous bolt catch paddle cutout, such as Rainier Arms, Mega, F4 Defense, etc. there is ample clearance for ABC/R v2, 7.62mm.Machined from billet 8620 alloy steel and heat treated with DLC finish. The ABC/R v3 is proudly designed and made in the USA.Starting from June 15, 2018, bolt catch plunger and spring are included.