if you´ve seen Saving Private Ryan you see there comes almost no blood when they shoot each other with rifles and SMG´s, but when they are in that last fight in the french town and the 20mm comes and shoots them on the tank there´s lots of blood and limbs shot of. So when there shot with rifles and SMG´s most of the bleeding is probably stopped by clothing.

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"...await the right moment for one, and only one well-aimed shot"
-Vasily Zaitsev