I'd like the hard stats, too; I've seen it inferred elsewhere, but was not aware of explicit polling (i.e. they extrapolate the demographics of new CHL permits or people who poll in opposition to gun control vs. last election & try to determine how many of them "would have" voted Democrat last go around, but didn't this time presumably from gun control).
The idea of gun owners costing Hillary the election is pretty straightforward, though, especially considering how the election worked out as far as popular vs. electoral college vote. Rural, sub-urban, and many red-state urban areas strongly disfavor gun control at this point, and her entire campaign was predicated on the blue metropolis' outweighing the representation of everyone else. In hindsight, it's a needless handicap to one's ambitions because of the amplifying effect the electoral college has on rural states (i.e. in specifically alienating those folks by chasing unpopular measures like gun control, you have effectively raised the margin by which you must win to at least several percentage points above a bare majority; a really dumb tactic when your only support comes from people who are quite unenthusiastic to start with)
To be fair, it's not all Hillary's fault, and the tactic worked great at half-rallying the base during the primaries. Though she certainly did her best to re-stoke the 90's era fires of gun control, it's not like we would have been any less leery had she kept mum like Obama during his run. I'd say a good 3/4 of the blame lies with her party which has made itself such a shameless tool of civilian disarmament, that onetime-Democrat supporters who have any fondness at all for the RKBA can no longer expect even cheap lip service from their party. Heck, even a slight majority of self-identified Democrats now disfavor an assault weapons ban, yet Hillary was talking about Australian confiscation; what a fiasco.
TCB