Pigcheese, welcome to TFL.
The tax deduction idea is an interesting one. I see at least two problems with it, however.
It'll never happen, at least at the federal level.
But even it it did, or if it were done at the state level, I'd be concerned that the idea that gun owners were "helping" law enforcement would spill over into the way that at least some gun owners think about themselves. Unfortunately, it's not uncommon for some to have a notion that a license to carry is somehow a permit to "play cop," rather than being about
self-defense. Whether you choose to carry a gun, or just keep one or more at home for defensive purposes, it's first and foremost about protecting yourself and your family, not about helping the community.
I think one might also make the case that either mandatory gun ownership or a tax deduction for same would penalize folks with less money, for whom the price of a reliable gun, and the necessary training to use it effectively, might be a heavy burden.
And I can see some potential for a vicious circle here: tax deductions for gun owners would mean less money in the pot, which would likely mean cutting funding for law enforcement, which would... you get the idea.