Project Sierra/SPECWEP

SPARTAN Assault Platforms, or S.A.P's, were experimental prototype small arms utilising much more powerful munitions than standard conventional military small arms currently in service. They were designed and created at ONI Shadow Base, the head of ONI's Technology and Weapons // Research and Development efforts and where designed explicitly for use by SPARTAN Commando's operating in MJOLNIR armour systems.

Overview
With the increasing amount of field reports concerning rounds and cartridges such as the MA5 Series Assault Rifle's [http://halo.wikia.com/wiki/M118_7.62x51mm_Full_Metal_Jacket_Armor-Piercing| 7.62x51mm NATO round being ineffective against shielded and moderate-to-heavily armoured combatants, Shadow Base, a sub-division of ONI Section III, began limited experimentation and production of both Assault Rifle's and DMR's chambered to fire much more powerful munitions. After extensive conceptualisation, experimentation and relatively limited field testing, the S.A.P Program was created.

MA37-50 Mk.0
The MA37-50 Mk.0 was the official designation given to a modified MA37 Assault Rifle that was rechambered to fire the | 12.7x40mm M225 SAP-HE 50.caliber round normally used in the | MG Series of standard issue handguns. The reason for this choice of round is down to its proven high effectiveness in penetrating armoured targets, high damage against shielded opponents and its High-Explosive nature, making it somewhat effective against vehicles and heavily armoured targets as well as being abundant and commonplace in armouries, battlefields and stockpiles alike.