Depends on what you mean by 'impulse' buy.
I collect old S&W revolvers and old Colt autopistols. I live in PDSR California, so all 'used' guns are actually person to person consignment deals. (Dealers can only sell new guns on the politically correct list.)
When a nice example of a S&W revolver shows up, they don't last long. So if I find one I want, if I don't buy it right now, it will be gone.
My soon-to-be-ex-wife could never understand this and constantly accuse me of 'impulse' buying. I explained the problem to her numerous times; she would look me in the eye, nod her head, sometimes repeat something I said, and never understand the concept.
I don't impulse buy 'new' guns. Frankly, not many new gun interest me.