The battle scenes are violent and realistic in most aspects, although, if anything, the effects of gunfire are underestimated. At the climactic battle, Katsumoto remains awake and alert with two .45 caliber exit wounds showing through his upper back (i.e., chest wounds) and has to beg Algren to help him commit seppuku. In another scene, a young samurai charges into rifle fire, taking at least a dozen hits at close range, only to gracefully slide to his knees and fall on his face, rather than being thrown on his back. One concern did not materialize—excess blood. Indeed, given the amount of combat, the movie is actually very bloodless. Katsumoto does not bleed from the wounds described above, nor is any spilled blood seen when Katsumoto assists the seppuku of General Hasegawa, or when they are stepping over the fallen bodies of Katsumoto's guards. The occasional bloodied nose or bloodied sword blade is seen, but that's about all.
I was interested by an article in the paper recently remarking on the ascendancy of swords over guns in recent films, including "Kill Bill," and "Return of the King," which caused me to realize that, despite the many battles and deaths in "Lord of the Rings," very little blood is seen. (This is helped by the fact that orc blood is evidently black.) Boromir doesn't get a chance to bleed from his arrow wounds, although if I recall, he does the cough-blood-from-the-corner-of-the-mouth thing, which is always a sign of a mortal wound in anyone but the protagonist. Haldir's death, his skull split from behind by an orc chopper, could have been bloody, but was not due to tasteful camera angles. Theoden is crushed beneath his fallen horse and Eowyn has her arm broken by the Witch-King's mace, both as written by Tolkien, which may imply that he had an aversion to having his heroes hacked to death. Tolkien does not describe Faramir's wounds, but in the film he has evidently been dragged by his horse with most of the damage being presumably fractures and contusions. Rohirrim, elves, and Gondorian soldiers die by the hundreds in the various battles, but, as extras should, it's in the background. All in all, keeping the gore level so low in both films really is a remarkable accomplishment.