The idea of a "safe" list means newer guns can be forbidden because they're not on the list. Anyone who's dealt with California's "approved" list knows what I'm getting at, and it's a sneaky way to close the pool of available firearms in a few years.
We have a "safe" list here in MA. To get on the list, manufacturers must submit to a long and costly testing/certification process for each "sku" item they wish to sell in MA. Many chose not to sell their wares in MA as a result. We have a substantially reduced pool of available firearms as a result.