Well, it was much simpler: it was World War 1, and there was a hard divide between handgun and rifle bullets which wouldn't really go away until 1938 when the 7.93x33mm Kurz was designed. The sub-machine gun (which is how the term was originally formed) was an even-lighter-than-light machine gun firing a handgun bullet rather than a rifle bullet.

In my experience, "battle rifle" is a subset of "rifle" which refers specifically to assault-like rifles that fire full-sized rifle bullets (ie FAL, G3, M14) and have at least a select-fire variant, otherwise it's hard to draw a line between a battle rifle and a DMR. If I remember rightly, the term is actually fairly new, and was coined in the Vietnam era to provide a distinction between the M14 "battle rifle" and the new M16 "assault rifle."

I believe what he means is that what the ammo is for doesn't change the class of the gun. So, for example, loading your M1911 with FMJs instead of hollowpoints doesn't change it from a "light attack pistol" into a "heavy duty pistol" (unless you live inside a videogame, in which case it probably does). Same here, putting AP rounds into what's basically a subgun doesn't really change that it's a subgun, it just addresses why subgun sales started to fall off in favour of compact carbines (the increasing likelihood of encountering bad guys in body armour and the relative crapness of the traditional 9x19mm subgun round against such) so companies could try to lure back their old SMG clients.

5.7x28mm was designed specifically with the P90 in mind, the Five-seveN pistol came along after. Likewise, the 4.6x30mm was designed specifically with the MP7 in mind, but in this case HK's companion pistol, the UCP, never materialized outside of limited trials with the Bundeswehr.

You're not telling me anything that I don't know (or didn't already demonstrate that I knew in my previous posts). I am well aware that the P90 and MP7 are intended to fit assault rifles' penetration capabilities into a compact package; you didn't need to write an editorial-length post explaining the differences between PDWs and conventional submachine guns. What you still keep failing to ask yourself is why this ability makes them distinctive enough to deserve an entire category. Contrary to manufacturers' hype (which you seem to be buying into), the fact that PDWs fire such ammunition does not make them revolutionary enough to warrant an entire class of firearms unto themselves.

Also, since the G11 example obviously failed to make my case, let me try this one instead: Think about the evolution of the revolver. First, revolvers evolved from black powder designs into cartridge designs, and then from single-action to double-action. Compared to the submachine gun/PDW distinction, those are some major changes, right? Yet IMFDB still classifies them all as simply "revolvers" - we don't even have sub-categories for "black powder revolver" and "cartridge revolver", or "single-action revolver" and "double-action revolver". Or maybe you think we should do that, too?

But anyway, separating PDWs (which represent a comparatively minor trend in firearm history) from SMGs would be almost as ridiculous as insisting that we come up with three new categories for revolvers. If you wish to argue for that, too, then be my guest.

Um, making incorrect edits is hardly grounds for banning by itself.

Right, but you are trying to add more rules and make things more complicated than they need to be (for the purposes of our site).

Which is what we're going to do, though I don't think it's an illegitimate debate to consider the value of a PDW category.

As Tim pointed out, PDWs have been around for a while now; the P90's name comes from the year of its introduction - 1990 - which means that it's been around longer than most IMFDB users have been alive. Since that time, it has been compact 5.56mm carbines - not PDWs - that replaced 9mm SMGs in most tactical teams' inventories. Based on this hindsight, I think we can say with certainty in 2011 that the PDW represents a minor trend in firearms that is unworthy of its own special and distinct category.

That's hilarious. I think it also goes to show why you can't always take the industry's own classification seriously. Indeed, I think Mazryonh himself demonstrated this when he pointed out that Colt described their Model 607 as a "submachine gun" (which is also how Daewoo describes the K1/K1A). In the case of PDWs, manufacturers have every reason to try and promote their weapons as some special and revolutionary new class of firearms, even though they're hardly worthy of such hype.

I think this by itself is a good rule of thumb when we're deciding whether or not to create a new firearms category: If there are THAT few, it probably doesn't constitute a whole new class of small arms requiring their own category.

In all fairness to Mazryonh, PDW doesn't seem as absurd a category to include as some of the others we seem to have. I had no idea, for instance, that someone made a category for "Multiple Barrel Firearm" and another for "Machine Revolver". Those should go, IMO. A lot of these unnecessary categories can be blamed on Cutaway (someone else who seems to have an obsession with making IMFDB into a firearms Wiki rather than a movie guns Wiki).

I'm going to yank "machine revolver" right now, I've encountered it elsewhere and it doesn't make any sense as a category: you'd never describe a Mateba or Webley-Fosberry as a "machine" anything, because they're semi-autos.

Could you nuke the category, MT? Also, can you nuke "Welrod Pistol?" Ben41 accidentally moved "Welrod pistol" to "Welrod Istol" and created a redirect on "Welrod Pistol" that prevents the article being moved there.

Sure thing. First I gotta also remove it from the pages it's on, though.

I don't so much mind having a cat for multiple barrel firearms of a certain type (rotary guns) since it makes it quicker to check through them all and it's a logical group, but I'd agree that the previous name was too broad; nobody really needs to look at all types of multi-barrel weapon to see if this minigun-looking thing they saw might actually be a double-barrel shotgun.

Took a look at the rest of the firearms categories. Most of them seem fine to me. There are a couple I'm curious about though, and since we're on it, let's discuss them:

*UBGL (Under Barrel Grenade Launcher): Not sure if we really need this when we already have "Grenade Launcher".
*Underwater Firearm: Right now, it's just the H&K P11.

Should I ditch these, too?

Underwater firearm seems pretty useless since there's only a handful in total, mostly either obscure prototypes or equally obscure Russian special-issue weapons; Wikipedia lists eight including the cancelled Lancejet and AAI's underwater revolver than never got past prototype. They don't tend to appear in anything since Hollywood has a strong preference for spearguns, and I really can't see the use of a category with only one gun in it.

UGBL is potentially useful. The way I use categories for guns, if I see a weapon I don't recognise I'll click around the entries in the cat looking at the page images before searching offsite. Obviously, if I'm looking at an underbarrel launcher I'm not likely to want to search through a list full of standalones.

Also, this still needs killing:

http://www.imfdb.org/wiki/Welrod_Pistol

True, but I just feel that the list of grenade launchers is short enough that this isn't a problem. This seems almost as unnecessary to me as the PDW category, even if there are way more UBGLs than PDWs.

Done. Thought I did it before, but I got logged out accidentally and prevented from making the change, but somehow didn't notice (blame it on multitasking and 'Net-induced ADD).

Also, for now, I'm leaving the PDW category up, but I am still leaning towards removing it.