Luth-AR MBA-3 Adjustable Butt

A few months ago I fitted the full-length, fixed, LUTH-AR MBA-1 butt to my SGC Speedmaster, 20” barrelled rifle. This clubfoot design features a height-adjustable comb and also a length of pull (LOP) adjustable butt pad. It’s similar in concept to the bigger, heavier and more expensive Magpul PRS (Precision Rifle Stock) and strikes an excellent compromise between price and practicality.

CARBINE CULTURE

However, full-length ARs are not that popular, with the generic, telescopic (sliding butt) of the CAR15 carbine being top choice. LUTH now fills this need with their MBA-3 butt! Essentially, it offers the same features as the ‘fixed’ MBA-1, though adds a few more too. Made of glass-filled nylon, it weighs 18oz and is rectangular in shape, with the front strap being concave to give a gripping surface.

It offers both LOP and comb/ cheekpiece length/height adjustment by means of thumb wheels, with LOP giving a 1.25” range with 1” on the comb height. New is the adjustable butt plate, which can be moved left and right, angled and positioned up or down to suit the shoulder fit required; clever stuff. It also offers a wider/deeper footprint than the MBA-1. LUTH includes an Allen key that clips into the butt for all settings as we shall see. On the base of the butt frame there’s an integral section of Picatinny rail, which is ideal for attaching a rear monopod.

 

PULL, SLIDE AND SCREW

Being a telescopic design, the MBA-3 has to slide forward and back to suit, which is controlled in the normal manner by a vertically sliding plunger. However, as LUTH have essentially modified their original design, there’s no large and easy to access latch as you might find on a Rock River Arms-type butt. Instead they have incorporated a small, pull-down plunger at the front/top of the frame cut out. Look closely and you will see a tiny slot in the rim, which has to be aligned with a section of the Allen key retaining moulding underneath it, otherwise it will not pull down far enough to clear the plunger.

The MBA-3 is designed to fit most commercial and military buffer tubes; we were supplied with a Leapers for the test. One thing is a bit confusing is that once on, there did not seem any way to lock the butt rigid. as it does wobble a bit. Investigation showed a small grub screw on the butt tube that has to be screwed in to secure it from moving. It’s a bit basic and not 100% rigid, but and apart from totally re-designing it seems to be the only solution.

In use, the adjustable LOP, combined with its telescopic ability offers a lot of possible movement, likewise the comb/cheekpiece. LUTH mould in sockets for steel ‘cup’ inserts that accept pushbutton, QD swivels, but annoyingly theses are extra! Once set up, the MBA-3 is a sophisticated compromise for CAR-15 systems, though does not have the instant adjustability of its competitors when locked in position!
Contact: North West Custom Parts, 0161 408 1155