Depends on the product. A pure game suppliment would, obviously, be set up as you mentioned, with pistols ETC in sections. A more realistic catelogue will, instead, group by manufacturer. If you grab a copy of Previews, for instance, the groupings are by publishing house (DC, Marvel, etc) rather than by type (Super Hero, Western, Harem Comedy, etc) ... Brand loyalty is a Thing.
Heck, for years... no, for *decades* I've wanted to see the Battletech line start listing mechs by primary House affiliation, rather than tonnage. If I want to know what mech models the Draconis COmbine is fielding, I want to be able to turn to the Draconis section of a book and grab the mechs for a unit from there, rather than flipping through all the lights, then all the mediums, and so on.
Different people have different mental filing systems is what I'm ultimately trying to say.
That said, and while I didn't work on the product, I want to thank you for buying it and for passing on comments, be they negative or positive. Silence is the one thing that's unbearable.
As an aside, would you mind dropping a list of, say, five books that are set up in a way that you think is quite useful to you? Not a "Must Have" thing like Augmentation or Unwired, but suppliments from any edition of Shadowrun where you can point at and go, "This, right here? This is what a sourcebook should look like." Always helps to know what people are looking for.
-- Wak