is the high power rifle thing because iowa is super flat? maybe thats why a lot of mid westerners bow hunt?Your state game regulations will tell you for sure. would think 20 gauge is as small as they would go. Beside a .410 is more expensive to shoot than a 20 gauge.
I shot deer in Iowa with a 12 gauge, not something that is easy especially if they are moving. Cant use high powered rifles in Iowa.