Lewis Machine & Tool

Lewis Machine & Tool ranks #21 of 342 brands on GunPartPicker so far in October 2026, just behind SureFire, with about 1% of every part builders added. Down from #19 in September. Builders are reaching for Lewis Machine & Tool mostly for lower receiver parts. The most added single part is the LMT MARS-L Ambidextrous AR-15 Stripped Lower Receiver, on top again this month.

Bolt carrier groups have not been restocked once this month. About 46% of the 154 Lewis Machine & Tool products we track are in stock today.

Also popular this month: LMT MARS-LS PDW Complete Ambidextrous AR-15 Lower Receiver, AMBIDEXTROUS 5.56MM CHARGING HANDLE, LMT Upper Receiver Assembly - AR-15 - M4 - Black Anodize and LMT Defense 5.56 F-A BOLT CARRIER GROUP.

In GunPartPicker builds

• #44th most added lower receiver brandTop part: LMT MARS-L Ambidextrous Stripped Lower

Why Lewis Machine & Tool

Karl Lewis founded LMT in 1980, and by 1986 it was building complete rifles for military and police sales overseas. It still makes service rifles, from the British L129A1 to New Zealand's MARS-L and Estonia's MARS-H, and does OEM work for other high end AR makers.

The MRP upper is what it's known for: the receiver and rail machined from a single 7075-T6 forging, with the barrel held by two T-30 Torx bolts so you can swap barrels in minutes. The Enhanced Bolt uses a two spring lobster tail extractor and a hard chrome coat.

The lowers are the other draw. The MARS-L puts an ambi selector, mag release and bolt catch right in the receiver with a flared magwell, and there are Defender lowers too. The MARS-H and MWS cover .308.

LMT lowers cost about $321 against roughly $213 for the typical lower, and they're fourth in the slot, on about 8% of builds that have one. Its bolt carriers run about $250 against $199.

The catch is price and lock-in. An MRP-L 13.25 inch upper is about $940 without a barrel, and it only takes LMT monolithic barrel assemblies. You're buying into LMT's system, not a standard upper you can rebarrel with anyone's parts.

In March 2025 Switzerland chose a MARS-L based rifle, the Sturmgewehr 25, for its special forces in 12 and 16 inch versions. In early October about half of LMT's listings across stores were in stock.

We'd start with a MARS-L lower if you want true ambi controls on a rifle you'll keep. Go MRP only if you'll actually swap barrels.