I think one reason why it did so good was because of the length it was away from the gun barrel. You might think that the closer you are, the more damage would be brought to the katana. In reality, because of the katana\'s unique shape and material, it might actually do the opposite.
When the bullets are coming out of the barrel, they are super heated from the combustion within the gun. When meeting the air, the bullet is cooled surely but not to a super high degree. If you have ever been to a shooting range, you should know that bullets are still pretty hot after about 20 seconds of being shot.
When this white hot bullet hits the curved blade, its very weak density wise. The bullets you can see in the movie move slightly upwards or downwards depending on the placement of the blade. This slides them and cuts them in half. Still amazing though, one small 4 foot blade could stop something so destructive. The sight is even more impressive after seeing that 50 cal just DESTROY that barrel.

the destruction just makes me so giddy.