<XMP><BODY></xmp> MARS round

Other than my own page, this is the only useful online text I've found about the MARS project:

“The Colt MARS (Mini Assault Rifle System) was conceived by LTC Michael R. Harris, AUS (ret.). His goal was to develop a weapon to replace 9mm pistols and submachine guns among the military, special police and security forces. The system, with its unique 5.56x30mm ammunition would match the speed and accuracy of AK-type threat weapons. Pivotal to attaining this goal was the development of a small, powerful cartridge capable of producing the energy and pressures required for an AR-15 type mechanism. This was accomplished by taking advantage of the higher-energy densities of modern ball powders, employing magnum pistol-type powders burned at rifle pressures. Mike took his cartridge and system concept to Colt Firearms. Colt engineers perfected a scaled-down weapon with an 11-inch barrel, collapsible stock and other unique internal features, realizing Mike's goals. The firearm and its cartridge were awarded patent number 5,827,992 on October 27, 1998. It was assigned to Colt's Manufacturing Company. During development three guns, various test barrels and experimental lots of ammunition were fabricated. The weapon system is not slated for commercial development at this time due to financial constraints. Our interest is focused on the special, patented cartridge that makes this weapon system work. Quoting from the patent we note “the modified firearm of the invention utilizes a novel cartridge which has been developed to provide a more compact weapon, while maintaining its lethality and increasing the number of rounds that can be carried on a mission without any increase in overall weight to the soldier. This novel cartridge also takes up less volume per round.” “The MARS cartridge is the center of the concept in developing the revolutionary system of the invention. Rather than the 55 grain M193 bullet with a Ballistic Coefficient (BC) of only 0.243, the 5.56x30mm MARS uses a commercially available 55 grain full metal jacket bullet with a BC of 0.272. This produces a flatter trajectory and retains more energy to deliver to the target than an M193 bullet launched at the same velocity. The cartridge is loaded with 16.8 grains of a commercially available ball powder to provide a 2600 ft/sec velocity with complete burning resulting in a low muzzle flash when compared to an M193 or M855 bullet (sic) fired in an 11 inch barrel.” “The MARS cartridge case is unique in the efficiency of the design. The 300m range, penetration and lethality are based on launching the 55-grain projectile at 2600+ ft/sec. The cartridge neck is only long enough to support the bearing surface of the 55-grain full metal jacket bullet, which runs from the cannelure groove to the slope of the boat tail. This is the shortest neck of any military cartridge.” “The angle of the shoulder of the cartridge, taken from a longitudinal axis thereof, is 30 degrees. This is the steepest shoulder that can be mass-produced and allows for maximum powder capacity. The body has less taper than the M193 or M855 bullet (sic) since the short case has less surface area friction to overcome during extraction. The case head and wall thickness retain military and SAAMI (Small Arms and Manufacturers Institute) specifications to ensure a safe operating pressure of 55,000 psi. The cartridge is loaded to an overall length of 1.7 inches. The size and shape enhance the feeding over the M193 and M855 type cartridges. Military and SAAMI specifications are used on 5.56x30mm MARS cartridge wall thickness to include side walls, shoulder and case mouth. Most of the experimental 5.56x30mm MARS ammunition that was ever produced has been expended in testing and demonstrations. Early production was on U S military brass with headstamps such as WCC 93 (NATO mark). Later rounds are based on commercial WINCHESTER and R - P 223 REM brass. Rounds observed to date have been Ball and Tracer (red tip M196 type) on commercial R - P brass, Ball on commercial WINCHESTER brass, and various types of Dummy on both commercial R -P and military brass. Magazine articles have also pictured or alluded to: 40-grain Blitz bullet, 40-grain VMAX, 62-grain SS109, 45-grain APDS (appears to be Armor Piercing Discarding Sabot). The label from a container of Ball loaded on R-P brass states PROTOTYPE COLT MARS CARTRIDGE CALIBER 5.56 CASE n/a BULLET TYPE W/W FMJ BULLET WEIGHT 55 POWDER TYPE 680 POWDER WEIGHT 15.8 PRIMER TYPE 7 1/2 SEATING DEPTH n/a VELOCITY n/a WARNING: LOADED ONLY FOR COLT MINI ASSAULT RIFLE AND NOT FOR USE IN ANY OTHER FIREARM. The next step in taking advantage of the MARS system was to be the development of same-length larger caliber rounds for close range, rapid incapacitation situations. Before the project was shelved two rounds had been prototyped which, in test barrels, developed the high pressures required to potentially operate the mechanism. Both rounds are loaded on Starline *---* 10mm MAG brass. The 9mm round has just enough neck to hold the 124-grain bullet, thus maximizing powder capacity, and is loaded to the same overall length as the 5.56 round. The 10mm round has a blunter, 180-grain bullet. It has been observed in loaded and no-primer dummy configuration. A partial label from the latter states PROTOTYPE COLT MARS CARTRIDGE CALIBER 10mm CASE Starline BULLET TYPE TC POWDER TYPE n/a PRIMER TYPE n/a VELOCITY n/a WARNING: LOADED ONLY FOR COLT M... RIFLE AND NOT FOR USE IN ANY OTHER ..... A duplex load with two 130-grain bullets was discussed but not seen.”

The idea of larger calibre 9-10mm rounds is interesting, since it parallels the Russian 9x39mm and some of my own ideas

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