Here is a link to an interesting online article that attempts to definitively say which are the 5 most popular guns and why they are such. The thing is, while interesting reading, with lots of references, the article fails to definitively say why the ones mentioned are the most popular. It even failed to convince me that the ones mentioned are the most popular although I will admit that I know at least 5 of them to be quite popular among buyers in the commercial retail market. I think that the author(s) of the article has confused things a bit by saying - yes this specific firearm is one of the most popular and here are the facts and figures on this one to prove it - then goes onto say - well this other one is among the most popular because a lot of them have been sold. There is a difference between those two methods of saying one is such and the other is such. Look at the Remington and then the Thompson for examples respective to how I just said it above, with the Remington they give hard cold facts as to how many were produced and sold but with the Thompson they say: "Many hunters and sportsmen consider its Encore 209x.50 Magnum to be the most versatile muzzleloader available today" but they never quote any manufacturing or sales bottom line figures. Heck they do not even say most, they use the word "many" to vaguely describe how many people find them, not popular, but versatile! Even with the Remington, they do not definitively say it has sold more than any other models just that 10 million of them have wound up in the hands of firearms owners (Wow, 10,000,000!). Seems they forgot right off they were supposed to be telling us why the firearms listed were shown as the most popular!
I think that maybe they just should have given the article another name like '5 Very Popular Firearms and Why'. Yet, I will admit, it would be one heck of a difficult assignment to write up the 5 most popular firearms of all time especially when trying to definitively explain such to a skeptic and cynic like me. As I said though, it is an interesting and good read and well worth the brief amount of time it takes to read it.
All the best,