Actually, it could be credible. (I doubt it, but it could.)
Think of it like this: Imagine there are 100 households in the US and 50 of them have guns. Now imagine that 10 more of them buy guns this year and at the same time you import 100 impoverished refugees. That means you started with 50% gun ownership, had more households buy guns, but ended with 30% gun ownership.
So long as I and all my conservative friends are well armed, I don’t care what the percentages are. In fact, the fewer liberal kooks who own weapons, the better.
Another possible explanation?
People refuse to tell them they own guns.
A reasonable thing to do?
Screw em, buy more guns and ammo. It is none of their business what we own.