If a country like the US had a lower violent dead per capita than other first world countries like France or Germany, I would agree with you. But given that the numbers are 3 to 6 times those of EU countries, it doesn't seem to be working.
Still, if you want to quantify how many lives were saved in any given year I can give you how many innocent ones were lost. Hard to measure, you say? Then it's a weak arguments based on feelings not facts.