The James Madison Tactical JMT Gen-2 is a polymer 80% lower receiver. It uses reinforced polymer construction with a black finish for corrosion resistance. The design includes an integrated trigger guard and reinforced takedown lugs for structural integrity.
This lower receiver is compatible with standard AR-15 upper receivers and mil-spec parts. It accepts standard AR-15 triggers, grips, and buffer tube assemblies. The polymer alloy meets SAE AMS-S-751 specification for durability and dimensional stability.
The lower ships with a machining jig for completing the 80% receiver. It requires milling of the fire control group pocket and selector switch hole. No FFL transfer is needed as this is an unfinished receiver.
Tolerances are within ±0.003 inches for critical dimensions. Weight is 4.7 ounces. The Gen-2 version improves on previous models with thicker wall sections at stress points.
Jake Morrison’s shop notes
JMT Gen-2 80% lower has a 0.625" rear takedown pin hole – undersized compared to mil-spec 0.626". Requires reaming for proper fit with most LPKs. Trigger pocket depth measures 0.860", cuts clean with carbide end mills but leaves thin walls near safety selector.
Tested: 863 rounds bench-cycled. Pocket tolerance measured: within 0.0008″ on this batch. Weight (actual): 13.5 oz on shop scale. Units shipped from Phoenix in March 2026: 99.
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