AR Reaction Block With Alignment Fork for TDP AR, HK 416 or 417

We’re huge fans of the Big Green Reaction Block that ensures the buffer tube is properly aligned with the lower receiver, but the HK 416/MR556 parts don’t fit. So, we developed this. It also acts as an alignment check tool.

We also developed a version for the TDP M4 buffer tube in the event the big green one is out of stock.

Then we came up for one for the HK 417 by customer request.

Choose which version you need in the drop-down list.

These are intended to be used with the Forward Controls Design JCW Joint Castle Nut Wrench available HERE. The built-in extension surrounds the buffer tube and precludes the need for a spacer to act against the wrench when applying torque.

Made from very serious carbon fiber reinforced high temperature nylon.

We also make a Roto-Reaction Block for TDP and HK 416 buffer tubes that allows 360° castle nut staking capability. Click HERE to see it.