A guide to the specialty ammunition created for the SPAS
SPAS Specialty Rounds
Part of the development of the SPAS lineup (12, 14, 15, and 16) included the ability for the SPAS guns to fire a diverse selection of rounds. So to highlight the dual-firing modes of the lineup and bolster the appeal of the flexibility of the weapon for programs like the US Navy's RHINO and CAWS, as well as to meet demands of Italy's Policia Di Stato - Franchi took matters into their own hands (with help from Fiocchi) to develop a SPAS signature lineup of ammunition for their revolutionary shotguns.
The rounds were split up in to two groups and color coded. The red cartridges denoted a "lethal" round, whereas the green cartridges denoted a "less-than-lethal" round - varying from rubber slugs, to nylon "close range" ammunition. This has also been confirmed as the reasoning behind the two colors of SPAS 15 magazines - ease of differentiating between which magazines were loaded with lethal rounds vs. non-lethal without removing the magazine to inspect each round. Green-marked magazines are exceedingly rare.
Most of the names of the specialty rounds have been found and translated as such:
The GP 27 - General Purpose 27 Pellet
Cartridge for general use has 27 pellets, capable of piercing a car door up to 25m, each pellet (137g and 6.1mm of diameter) retains its sphericity after the impact, with high lethality.
The GP 9 - General Purpose 9 Pellet
Able to pass a car through and through; each pellet weighs 3.72gr and a diameter of 8.6mm.
The GPS - General Purpose Slug
Bullet capable of piercing a car longways, from the trunk to the engine, even at 60m, weight 31g,
The MPS - Metal Piercing Slug (More info on the MPS below)
Effective bullet against light armor, anti-bullet glass, weight 33g, the MPS is capable of drilling a 42mm Saint-Gobain glass panel, or a 10mm steel plate.
The Rub S - Rubber Slug
5.8g rubber bullet special ammunition for law enforcement
The GPR18 - General Purpose Rubber 18 Pellet
Special ammunition for the maintenance of order; Each rubber ballet weighs 1.06g for a diameter of 8.5mm. 25m range.
The SR round - Short Range
Ammunition for shooting at very short distance while maintaining order; It contains 210 nylon balls of .04g. The maximum useful range is 5m, and this ammunition is used in Italy inside prisons
Left to Right - Note the Fiocchi branding
7 1/2 shot, GP 27, GP9, GPS, "Demolition", MPS (or Armour Piercing), GPR18, SR round, The RUB S, last three are CS gas variants (marked "tear" and "irritant")
The Metal Piercing Slug
The round which seems to have drawn the most interest was the SPAS MPS or Metal Piercing Slug.
Developed for use against armored targets, or those sporting bullet-proof glass - the MPS could reportedly poke holes in targets through steel plate over 1/4" thick.
The MPS may have gotten an evolutionary change, as in researching we noticed the MPS's marked "SPAS 12" had a more typical slug-look while later articles featuring their use with the SPAS 15 had a "rocket-shaped" look and were simply referred to as "Armor Piercing."
We have reached out to Fiocchi in hopes of clarification and will report back if new information is found.
5 MPS rounds from 20m at 10mm steel plate.