File:Marquis RDU-54 (Muscatatuck).png

Marquis RDU-54/RDU-59

Following the most recent conflict, the Ordinance Department proposed a universal rifle concept. A rifle meant to function as a SMG, LMG, DMR, carbine,nand standard infantry arm. To accomplish this the proposal took the 6x63mm cartridge already in use and shortened it to 6x40mm, took the action design from the in service LMG and inverted it, and finally packaged the system in as compact form as possible. The result was the RDU-54, rifle-downward ejection-universal-1954, which had a barrel of 25.5inches, overall length of 37.4inches, weight of 9lbs, and magazine of 24 cartridges. The rifle was torn down for field stripping by pushing the rear of trigger guard forward the swinging it around in lever fashion to release the rearmost lug on the barrel to allow the upper to be pivoted up releasing the rear receiver lug from the stock, from there the upper receiver stamping is shimmied off the barrel lugs there by the barrel and bolt assemblies are released out of the upper. Trials commenced and various alterations occurred resulting int the RDU-59 production model, the major difference being the rear half of the stock and its accompanying metal inserts being swapped in for a lower fabricated stamping. This new rifle being 29.8inches long with a barrel of 17.9inches, and weight of 8.2lbs.

The 6x40mm Rayon cartridge while intermediate in name was more equivalent to a light battle rifle cartridge being capable of 2017ft-lbs(2.74kJ), however, it was a lighter cartridge than its direct predecessor. The action being based on the in service LMG consisted of gas driven short stroke piston long travel multi-lug rotating bolt guided by overhead spring system and upper receiver stamping. Being a downward ejection the extreme length of the action required it to be placed aft of convention and as such resulted in a longer than anticipated development cycle to prove the system would function as reliably as it had before being shrunk down from the LMG which had the action ahead of the trigger group.

The functional groups of the rifle consist of trigger guard based safety similar to a M14 in which forward is safe and reward(within the trigger guard) is safe. The semi-auto to full-auto selector consists of a eccentric dime wheel which can be turned by finger nail, dime, corner of dog-tag, etc, and functions by enabling the auto sear.

Condensed Specifications:

RDU-54 First fired: May 6th 1954

Cartridge 6x40mm 108grain@2900fps / 7gr@884m/s

Action: Short stroke gas piston/long travel multi-lug rotating bolt

Weight: 9lbs (4.1kg)

Overall Length: 37.4inch (.95m)

Barrel Length: 25.5inch (.65m)

RDU-59

In service April 22nd 1959

Cartridge 6x40mm 108grain@2900fps (7gr@884m/s)

Action: Short stroke gas piston/long travel multi-lug rotating bolt

Weight: 8.2lbs (3.7kg)

Overall Length: 29.8inch (.76m)

Barrel Length: 17.9inch (.45m)