Honestly I’m a bit shocked that you don’t think a 10% reduction in gun deaths would be a big deal. That’s 3,000 people a year. The economic cost alone is enormous. Even if you can’t achieve a 50% decrease without repealing the 2nd — which I would contest — starting at 10 or 20% is not a problem in the least.
The all-or-nothing approach to gun control seems to be a position almost entirely occupied by the American right wing. Nowhere else do you see the idea that gun control is either about taking away all guns or it’s completely pointless, because that’s obviously a nonsense proposition. Politically — as I’m sure you’re aware — repealing the 2nd is completely impossible. So your suggestion that any ‘significant’ reduction relies on this step could quite easily be read as “let’s not do anything about gun control”.
I think preventing 3,000 deaths is significant. It wouldn’t even be that pricey.