M14 rifle.
The M14 was a 7.62 millimetres very accurate and very powerful rifle, but with a very strong recoil too. It was considered a standard rifle with regard to it's era, but under nowadays standards it's considered a high-caliber weapon for long-range engagements.
Some SOG soldiers liked to use it as a sniper-rifle, because with its twenty rounds magazine and selective-fire capability, it offered a higher volume of fire with respect to it's 'rival', the much more accurate M40.
It was Coletta's weapon's of choice.