"What difference does it make what kind of targets or ammo you shoot?"
You're joking, right?
It can make a HUGE difference because perception is all to often more impactful than things like the truth.
More and more ranges are no longer allowing "human" shaped targets.
We've all seen the Osama Bin Laden targets. Most people chuckle about that.
But how much good would it do if a group like Stormfront came out with their own line of targets showing prominent African Americans?
Think it would matter then?
Think people who aren't gun people would stop long enough to make a distinction between "racist *******s" and "general gunowners," or would they simply rush to judge?
In many communities, no they wouldn't make that distinction.
While zombie targets and ammunition may not really detract from the general perception of gunowners, they certainly don't build on it, either.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.