Re: Don't see their successes
"I don't define success as convictions for gun murders."
It would be a lesser type of success. But wouldn't you agree that a conviction for possession that prevented the murder would be a success?
Initially yes, but in the long term I would define success as even these prosecutions becoming vanishingly rare because the behaviour is eliminated. The obvious measure is reduction in murders...
Note that I don't say elimination, which would of course be ultimate success, but I doubt complete elimination is possible in even this relatively easy case (there are precious few reasons for people to have weapons - there is no reason for a sporting rifle/pistol to be outside of a locked box other than in a range).