The usual counterargument is to point to Switzerland where almost every man has an assault rifle at home and who are #56 on that list. I'm not saying that the trend you note doesn't exist, just that you need to look at more than a handful of data points to discern it and there are outliers which are frequently used to raise doubt about the trend.
If you look at murders with firearms however you find that Switzerland has a count about 4 times higher than the UK although their population is only about 12% that of the uk.
TTFN,
WK
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