The SG 542 was a fixed-stock battle rifle development in the SG 540 rifle series except chambered to fire the 7.62x51mm NATO round. Though an adequate weapon in its own right, the system never found the favor in export orders the way that the SG540 5.56mm type did. The SG540 series, as a whole, was a direct attempt to improve upon the preceding SG530, simplifying the breech mechanism and making the new weapon series cheaper to produce and thusly more fiscally responsible on the commercial market.
The SG542 fired from a 20- or 30-round straight detachable box magazines. Muzzle velocity was reported at 2,690 feet-per-second and a cyclic rate-of-fire of 650 to 800 rounds could be reached. Beyond the SG540 and the SG 542 existed the SG 543 which represented a shortened version of the base SG 540 and featured a folding butt.
Outwardly, the SG542 was a highly conventional rifle. As a "battle rifle" it simply incorporated the rifle-caliber cartridge into its design and, thusly, the internal mechanism had to be reworked to accept and fire the large powerful round. The cartridge allowed for engagement of targets beyond the range inherent in the 5.56mm cartridge while also providing selective, repeating fire in the process. Attaching a scope to the upper receiver and the SG542 could be used by a squad-level sharpshooter or designated marksman. The receiver held all of the major internal working components and included the feed mechanism as well as the trigger group. The forend was shrouded in a smooth casing which encompasses the top-mounted gas cylinder and the low-mounted barrel assembly. Sights were affixed at the rear of the upper receiver and the extreme end of the gas cylinder. The barrel was capped by a flash suppressor. The stock was fixed in placed and ergonomically shaped.