MDT Chassis Systems LSS-XL GEN2 Chassis System


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The original LSS-XL Gen2 chassis system was designed as a variant of our highly popular LSS chassis. The LSS chassis was designed for use with compact, short barrelled rifles. Many customers liked the LSS chassis, but wanted to use a fixed buttstock, and get their bipod out further forward.

This prompted us to design the first-generation LSS-XL chassis system, which has a forend extended by 3″ and was designed to accept fixed rifle stocks without the need of using any adapters.

After the successful launch of our ESS chassis system, requests started pouring in for the new features that had been introduced on the ESS chassis to be rolled out on our other chassis systems. In response, we have upgraded our LSS-XL chassis line with a Gen2 lineup that incorporates the following new features:

  • Bold, modern new look
  • Ambidextrous magazine release
  • Thumbrest above trigger guard
  • Larger barrel channel to accommodate barrels up to the diameter of the action
  • M-Lok pattern attachment slots on all five sides of the forend
  • Barricade-stop grooves ahead of mag-well
  • Side-relieved mag well to accommodate bulging magazines
  • Carbine and fixed buttstock interface options

The chassis is designed with V-shaped bedding surfaces, allowing you to drop your rifle right in without the need for additional bedding. The bottom profile of the V-block cutout has been kept round and close to the action without making contact, maintaining maximum strength. The LSS-XL Gen2 chassis will free float barrels up to 1.350” / 0.034 m diameter.


The LSS-XL Gen2 chassis are designed to accept any AR-15 buttstock and pistol grip (purchased separately), offering the option to customize from the wide variety of Accessories available on the market.

The LSS-XL Gen2 chassis accepts AICS-pattern external box magazines, and supports the installation of M-Lok patterned accessories along the forend.

Note: Long action magazines come in 4 different lengths: 3.560” / 0.090 m, 3.715″ / 0.094 m, 3.775″ / 0.095 m  and 3.850″ / 0.097 m. Unless otherwise specified, our long action chassis use 3.715 length magazines.

The chassis will accept recoil lugs up to .350″ (8.9mm) thick.


  • Increases accuracy by up to 21%
  • CNC Machined from 6061 Aluminum
  • Cerakote finish in Black or Flat Dark Earth
  • M-Lok pattern attachment system on all 5 faces of the forend
  • Carbine buttstock interface option designed for carbine AR-15 buttstocks, including the MDT Skeleton Carbine Stock
  • Fixed buttstock interface option designed for fixed AR-15 buttstocks, optimally the MDT Skeleton Rifle Stock V5
  • Accepts most AR-15 Pistol Grips
  • Lightweight, free-floating modular forend
  • Will accommodate barrels up to 1.350″ / 0.034 m diameter
  • Compatible with AICS style magazines
  • Weight: 1.6lb / 0.725 kg  – 2.0lb / 0.907 kg, depending on the rifle model


The LSS-XL Gen2 chassis system comes as a 1-piece chassis, with all required mounting hardware included. This includes new action screws, and a screw for the pistol grip.

To complete this chassis on your rifle, the additional items you need to purchase are:

  • Any AR-15 buttstock.
  • A buffer tube for your buttstock. (Both mil-spec and commercial work on our chassis)
  • An AR-15 Pistol Grip. For fixed interface chassis, a grip without a beavertail, or with a soft (bendable) beavertail must be used.
  • At least one magazine



Only our polymer magazines will work in the short action rifles due to the flat bottom. The long action rifles will work with the metal 3.715″ / 0.094 m magazines without fitting. For .223 models the bolt stop prevents the bolt from moving back far enough to pick up the rounds. This can easily be modified by removing the bolt stop and trimming the contact face.


For .223 models the bolt stop may be too long. This can easily be modified by removing the bolt stop and trimming the contact face.

SAVAGE MODELS 10/110 11/111 12/112 16/116

For rifles with the bolt release at the bottom, the bolt release can be engaged through the side of the chassis, using a pin or tool. (Not included)


Savage Long Action chassis systems all use 3.715″ / 0.094 m AICS magazine wells. The BA in 338 Lapua Magnum uses 3.850″ / 0.097. m magazines and have recently switched to a thicker recoil lug which will not fit our chassis. The ESS has been specifically designed around the current BA 110 in 338 Lapua Magnum.


Only our Metal 3.560 magazine will fit with the chassis for this action and needs to be purchased separately.


The action screw is located directly above the magazine lever. This means that the magazine lever needs to be installed AFTER installing the action into the chassis. Detailed instructions are provided, and an installation video can be found here. Ruger American in 223/5.56mm requires the use of a magazine with extended feed lips, such as this one: This is to prevent the round from being released before entering the chamber.

Does not work with 300 Blackout

This chassis will also accept the Predator and Ranch versions. Please read the notes above regarding magazines for 223/5.56 rifles.


Dimensions shown are based on Remington 700 Short Action.

mdt lss-xl fixed interface dimensions

mdt lss-xl carbine interface dimensions


Additional information

Weight 0.00000000 oz


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