Pistols
Level 1 - Pistol: Already available.
Level 2 - Silenced Pistol: Ryan Roth mission, Florida. Found during the mission where he sends you to rescue one of his soldiers.
Level 3 - Delta M1911 silenced : Mangano's Compound, Florida. Search the second floor.
Rifles
Level 1 - Sniper Rifle: Already available.
Level 2 - Spitzer Centerfire: Emilio's packing company, Florida. It is located on the rooftop; an engineer is required to cut the fence.
Level 3 - Vintovka SR-98: Almeida Compound, Cuba. On the second floor on a desk.
Shotguns
Level 1 - Shotgun: Already available.
Level 2 - Sawed-off: Corleone's Compound, New York. As soon as you leave the compound through the main gate, go straight forward, and turn left. There is a hedge that can be burned with an arsonist. The shotgun is behind there.
Level 3 - Schofield Semi-auto: Global Storage Chop Shop, Florida. On the right side of the island, inside the small warehouse.
Attack combos
Arm break : Press RB(3), LB.
Kick to shin: Press RB(2), LB.
Knee to groin: Press LB(2), RB.
Neck punch: Press LB(3), RB.