I would expect sales of firearms would outstrip NICS background checks because NICS checks reflect new shooters only. If existing shooters purchase a second firearm, they are not counted in the NICS check. So NICS checks understate firearms sales by a wide margin. NICS checks could be flat, or decline, and firearms sales could surge.
Yes, that has been the case for RGR, at least since I've been following it. Their Sales Growth beats the Adj. NICS Growth by a hefty amount. They always say it is because they are taking share, but I think a little of what you just said is at play also. It is going to be a blowout quarterly report !