there is no appreciable difference between many AR-15 type guns and many light hunting rifles other than the cosmetics.
So you are saying that a ban on AR-15 type guns will have
no detrimental effect whatsoever on people who want to own and use guns, and is therefore completely harmless?
Why the staunch opposition to it then?
You say it will have no effect - that the people who want these things can replace them readily with something of identical functionality, that's only cosmetically different.
Others say that it will have a beneficial effect on your society.
Given that testing which of these is correct cannot gave a significant negative outcome, but could have a significant positive outcome, the smart move is to collect high quality baseline data; Enact a temporary ban; And make that ban permanent if the post-ban data shows even the tiniest of benefits (because any benefit, however tiny, outweighs a purely cosmetic detriment).
To argue against a ban on AR-15 type guns from the position you have outlined, you would need to claim either that not one single life could be saved, nor death prevented; Or that the joy of owning a merely cosmetically enhanced rifle outweighs the value of a human life.
Neither claim seems to be anywhere close to plausible to me. The former could easily be tested (but you are apparently opposed to such testing on the grounds of a slippery slope fallacy, and general paranoia); The latter is morally bankrupt.