Well, back in the day, when men hunted for food vs drove to the supermarket, there was some merit to that statement. One gun, one use, and they were very familiar with their setup, vs the fellow with a handful of play toys.
Yes. About half a century ago, when I was a young student working a summer job in an isolated 2-man camp in Northern Ontario (50 miles from anywhere, and no radio - just a floatplane visit once per week to deliver supplies), my senior partner, a mid-thirties aged Native Indian, announced that a bear was stalking our camp, attracted by the food, which had to be stored inside ourSINGLE tent. He said we needed to kill it that NIGHT because once we headed off to our worksite on a survey grid in daylight, and the camp was unprotected, the bear would tear the tent and everything else to pieces getting at the food and making the most of the rare dining experience. He said most bears were leery of approaching humans or their camps, but when hungry, all bets were off, especially when the humans were absent, and apparently bears had been having a rough time in terms of food that season.
I asked him how we could kill the bear, given that our employer's policies prohibited any firearms in the camps. He casually pulled a rifle that had been hidden inside his 4 foot heavy sleeping bag (Down, no compact lightweight synthetics back then). I was somewhat relieved, until I realized, to my horror, that it was a .22 rimfire.
I asked him if he was seriously saying we would shoot a bear, and kill it, with a .22 rimfire, at night. He told me he had done it before and I need not worry. Yeah sure.
We heard the bear moving outside later, reasonably close to the tent. The Indian picked up the loaded rifle and told me he needed me to carry the Coleman lantern and hold it high in front of me. We started walking towards the bear. I had serious misgivings, but hey, I was 17, he was experienced AND Native, and he seemed very calm about the whole thing.
As we walked forward, I eventually could see why the lantern was key - I saw a pair of eyes reflecting the light. The Indian had us stop walking, and told me to hold the lantern very still. He aimed and fired. The eyes disappeared. He told me we needed to walk forward towards where the bear had been, and to keep the lantern high and forward. As we walked, I began to see a dark shape on the ground, and he put a few more shots into it, but kept some ammo in the rifle. Then we came right up to the body. He had indeed killed it. I was very impressed given that it was with a .22 AND I couldn't even see much of anything but the eyes when he fired.
We then spent a less than delightful number of hours digging a hole for the carcass, as he told me that the carcass MUST be buried, and deep, so as to not attract any more animals. That was not fun, but we got it done.
No further bear trouble fortunately.
I have not exaggerated in the slightest. The Indian obviously had lots of relevant experience. (As further evidenced by his smuggling the rifle into the workplace camp in the first place)
So, yeah, I believe that a man with one gun can indeed become very proficient with it, and can surprise both an adversary and any observers.
Jim G