What are you talking about? I assume we are talking about America because you say “regulations in America”. Handguns are the most commonly owned firearm in the US. So hardly a group of “small, special interests”. It is nearly 3/4 of gun owners. If you only own one firearm, handgun owners outnumber the next group of owners, rifles, nearly 3 to 1.
I can’t find what I would consider reliable numbers on number of “assault rifle” owners. I’ve seen 5-10 million AR-15 owners as estimates in large publications. The AR-15, while the most popular, is only one of 100s of various makes and models out there. So I can say it is probably at least 10% of gun owners who own one, but I can’t say how much more than that. I guess the statement that group of owners is “relatively small” as a percentage of overall owners may be fair.
