Friday, March 11, 2005

Framing the Issue

No, this isn't about "the issues" in the political sense, it's about the issue of gun frames.

A common question for those new to the gun world, or even those who've been in it forever but have little experience with newer guns is; "what are the advantages and disadvantages of various frame materials"?

There are five materials most often used for firearms frames (and recievers):

  1. Carbon steel
  2. Various titanium alloys
  3. Various aluminum alloys
  4. Stainless steel
  5. Various polymers
There have been a few frames made from carbon fiber (STI and Viper notably), and a couple of weird specialty items like magnesium frames (light, but easily cracked, and flammable) beryllium frames (which are actually toxic if not finished properly), or modern damascus frames and slides (pretty, but ridiculously expensive).

In terms of cost, polymer is very definitely the lowest production cost, and the lowest material cost. They are also lighter, and although they aren't as strong (though they can be close) because of their elasticity they can actually be tougher in some ways then the metal frames. Oh and of course they dont corrode with normal sweat or precipitation.

The disadvantages of polymer? Well they have to be made thicker and chunkier to be strong enough. This means they tend to fill the hand more, and they tend to be bulkier in general. Also they CAN crack at very low temperatures, or with very sudden shocks (like an out of battery fire). Finally, they generally don't offer a great grip, and most of them dont have changeable grip panels, so the best you can do is sleeve them, which makes them bulkier, or put adhesive grip tape or something similar, which can tear your hands up.

Titanium is by far the most expensive material, especially the titanium scandium alloys that S&W and Taurus are using. The advantage, they are strong, and light, so you can make a 1911 thats 4-6oz lighter than a carbon steel framed gun. The disadvantage? Titanium is expensive to buy, difficult to cast or forge, difficult to machine, difficult to finish etc... That means EXPENSIVE guns. Also Titanium work hardens and cracks far easier than either steel or aluminum. This isnt to say it's going to crack under normal use, jsut thats it's mroe likely tha with steel or aluminum.

Aluminum alloys are relatively inexpensive (though still more expensive than steel), and are a very common material for long gun recievers (especially shotguns), but are relatively rare in handgun frames other than .22's, with the notable exceptions of SIG, Ruger, the Colt Commander (and Officers ACP) and its clones.

Aluminum is a bit easier to forge and to machine than steel (though actually more difficult to cast, but its a well understood and mature technology so it makes little difference). The problem is, aluminum isn't very strong for it's volume; i.e. a piece of aluminum machined into the exact same shape as a piece of steel, will be a hell of a lot lighter, but not nearly as strong. This means you make it thicker, or you treat the metal in some way (generally by using a good solid forging in the first place, then specially heat treating it, and giving it a very hard finish). Also aluminum is prone to scratching unless it recieves a hard finish. Finally, aluminum wont last as long in high impact applications as steel; peening, cracking, or warping long before steel will, and at lower temperatures and pressures.

Stainless steel has become the material of choice for many firearms aplications, because it is corroison resistant, and slightly scratch resistant. It's a fair bit more expensive than carbon steel both in material cost, and in machining cost because stainless stell tends to be harder than carbon steel. Also because it is harder it can gall against plain carbon steel surfaces, and it is a little more likely to crack. It's also more difficult to finish stainless, so most stainless guns are left in the white, either polished, media blasted, or brushed.

Finally you get the traditional material, carbon steel. It's strong, it's resiliant, and it's cheap. Unfortunately its also heavy, and it corrodes very quickly. Since it's the tradtional frame material, it's characteristiics are pretty well understood, and theres reall not much special to talk about.

Oh, there's one more disadvantage to polymer: It's ugly


There's one more advantage to a nicely finished piece of carbon steel: It's pretty

Well finished aluminum, titanium, and stainless can look great, especially on a high end meltjob where the metal itself is rendered into almost a work of art; but there's just something pretty about a deep mirror blue, a rust blue brown; or my favorite for classic arms, color case hardening.