Based on the groundbreaking anime Blood: The Last Vampire. Blood+ is the epic story of Saya Otonashi, a teenage amnesiac who must regain her memory if she's to destroy the Chiropterans, a vicious horde of blood drinking shape-shifters that have plagued Japan for centuries.
During flashbacks of Saya's past in Vietnam, US soliders are carrying M16A1 rifles. The soldiers fire these weapons at Saya when she is going berserk, but the rounds do little to slow her down.
M1911A1
Saya's father George owns a M1911A1 which is seen drawn during flashbacks scenes with him and Saya. George mentions that he is ex-US military, so it's likely he kept this weapon after leaving the military. Kai later takes this weapon to chase down the Chiropteran that attacked and wounded George. He fires the whole magazine at the Chiropteran, but the rounds have little effect as the Chiropteran regenerates its wounds. David takes this weapon away from Kai, but gives it back to him later in the series so he can protect himself.
Smith & Wesson Model 500
David carries a massive Smith & Wesson Model 500 as his primary arm in most parts of the show. A handgun this size may seem unconventional for an agent to carry, but since Chiropterans cannot be killed by conventional means, Red Shield agents have to rely on the knock down power of their guns to keep them at bay.
Colt Model 933
After Saya's first Chiropteran encounter, a U.S. Special Forces team armed with Colt Model 933 carbines, secures the area. Later, Lewis is seen weilding a Model 933 when Kai approaches him on his motorcycle. In both instances they are fitted with Surefire M900 weaponlight foregrips and EOTech red dot sights.
Franchi SPAS-12
When Saya, Hagi and David go to rescue George, David equips himself with what appears to be a Franchi SPAS-12 with a removed stock and loaded with slug rounds. Lewis mentions that this weapon is not enough to kill a Chiropteran, but David comments that it's all he needs because Saya is the ultimate weapon against Chiropterans. In Episode 12, Red Shield agents McCoy, Spencer, and Rogers all carry SPAS-12s when the group assaults the Cinq Fleche facility in Vietnam. Lewis also uses a SPAS-12s on various occasions throughout the series.
M79 grenade launcher
When David is selecting his weapons before going to rescue George, a M79 grenade launcher is seen the gun case.
When David is selecting his weapons before going to rescue George, a rifle that resembles a Barrett M82 is seen in the gun case.
AK-47
An AK-47 is seen briefly when Saya's school visits the Vietnam War museum in Episode 10.
Tokarev TT-33 Pistol
When reporter Akihiro tries to sneak in into the private school in Vietnam, he is caught and held at gunpoint with a Tokarev TT-33 Pistol.
Browning Hi-Power
Red Shield agent Rogers draws a Browning Hi-Power when a Chiropteran jumps on McCoy.
Notice that he doesnt have the hammer cocked meaning the pistol wouldnt fire in real life because its a single action only like the m1911, a common mistake amongst film and anime makers.
M1 Carbine
An M1 Carbine is seen briefly when Saya's school visits the Vietnam War museum in Episode 10.
Red Shield Agent Clara carries a M249 SAW in Episode 12, often seen firing it from the hip in an unusual fashion; using the carrying handle instead of the handguard.