7.62x33mm Caseless is an advanced ballistic ammunition type currently under testing and development by Solas Tempus R&D.
On the first of September, Solas Tempus R&D began searching for ways to reduce the weight load on smartgunners. One of the more ambitious projects was to turn the then-standard MG round, the 7.62x51mm M118 AP-FMJ round, into either a polymer-cased telescoped round or a full-on caseless round. Using propellants and materials on hand, engineers were able to create a combustible plastic-cased telescoped round measuring in at 7.62x45mm overall, with a weight reduction of roughly 25%. However, Solas Tempus came upon examples of high-grade futuristic propellant and ammunition, achieving performance previously thought unimaginable for the propellant volume. Far outmatching the M118 in ballistic performance, the powder and HE-I/AP round of the example 7.62x63mm brass-cased rounds were incorporated into the then-7.62x45mm telescoped cased round. During controlled testing, however, they found that the longer case did not incorporate a full powder load well, as the chamber pressures generated were significantly higher than what the 240ST was designed to handle. Thus, they tuned the new round down to roughly M118-levels, both performance-wise and chamber pressure-wise, which resulted in a new round: 7.62x33mm "caseless". This represents a weight savings of almost 55% over the original M118 round, while retaining better terminal ballistic performance and a more effective armor-piercing explosive projectile.
The entire round measures no more than 7.62x33mm, with the bullet itself being seated inside of the casing and surrounded by advanced propellant. While not "caseless" in the traditional sense, the polymer casing, primer, and new polymer belt links are all entirely combustible, meaning that 240STs modified to fire 7.62x33mm do not eject cases or belts, enhancing reliability and reducing footprint. A working prototype 240ST in 7.62x33 has been made and it is currently undergoing late-stage testing for production. Additionally, engineers are working to find a working personal defense weapon application for the round to supplement phaser pistols.