One of the main characters, Seras Victoria, wields in the beginning. The "Harkonnen", a 120lb sniper made especially for her that fires 30mm rounds, and then dual-wields the Harkonnen MK II, and a belt-fed automatic version of the original. The results of using both guns are bloody.
This is without a doubt one of the most violent anime of all time, and it's not for the faint of heart.
Massive amounts of extreme bloodshed and graphic gore in every episode. However, the violence becomes much stronger and more frequent as it goes on.
Examples: Several soldiers and civilians are bitten, blown up, shot to death, torn apart by gunfire and other means, burned alive, disintegrated, staked, sliced up by knives and swords and bayonets with extremely large amounts of blood.
The Millennium's attack on London can be very disturbing, since it involves vampire Nazis bombing the city, burning many innocent people alive. The Nazis also gun down several people and bite others, turning them into ghouls (zombie-like creatures that mindlessly eat and rip apart other people), and slaughter large numbers of people, with a TON of blood indeed.
To end a very bloody battle, a character grabs another character by the head and grates it against a wall while running full speed down a corridor until the character's head is just a shred of flesh with an eyeball. A massive bloody smear is left behind, and in another episode, in a somewhat similar scene, the protagonist devours a man alive, with incredibly extreme amounts of blood and gore being shed in the process.