Adventures in 9mm

Today is a march down history through various ammunition that is all nominally 9mm. Seems simple and straightforward, but we have some twists and turns!All of the brass (except complete cartridges) has been fired. I pick up the brass in my stall at the range and sometimes I get some brass that I myself didn't shoot which is how I get some other sorts of cartridges.I'm not going to go by size, but rather by date of introduction.

.38 S&W (9x20R)

The oldest design is the .38 S&W. It's the one with the bullet still in place. This was originally designed back in 1877 as a black powder cartridge. Something to know about black powder is that it has a lot less energy than the modern smokeless powders -- we'll see this difference again in a bit.You can tell this is a revolver round because it has a rimmed case. The rim is the ridge at the bottom of the case.This is also a nice segue into the why .38s and .357s are the same size -- and it has to do with case, bullet and chamber design. The outside of the case of a .38 is actually .38 inches. The inside of the case is smaller due to the wall thickness. The first cartridges had the bullet flush with the case -- this requires a heeled bullet. The advantage of this design is that the barrel is nothing more than an evenly drilled hole. The disadvantage is there's no good place to put lubrication for the lead bullets of the era. With the straight-sided bullets you can put the lube inside the case where it doesn't get all messy.In this case though the bullet is 0.361" -- a scoch bigger than the 0.357 in the current vintage.As time passed the .38 S&W got filled with the more potent smokeless powder and it was in service well into the 20th century.Next up:

.38 Special (9x29R)

This is the bigger badder brother of the .38 S&W. (Actually, I'm lying -- it's the bigger brother of the .38 Short Colt but I don't have one of those. That being said they look almost identical.) It's a 9mm longer (1/3 inch) then the older cartridge to hold more of the black powder. It's "special" since it's more powerful! This was introduced in 1899.By this time though smokeless powder was starting to become more common. Within a year of it's introduction they filled the case with the more potent stuff -- but now the case winds up being around half-empty. This will be remedied shortly. ;-)9mm Parabellum (9x19)Parabellum refers to "Si vis pacem, para bellum." "If you wish for peace, prepare for war." It was designed by Georg Luger (which is why it's sometimes called a 9mm Luger) for the a German arms shop in 1902. This was the first of the rounds here that was designed from the beginning to use smokeless powder.This is also the first of this set of rounds that was designed to be used in an auto-pistol. It has the classic rim of an auto-feeding round with the extraction groove by the rim. Even though there is a rim, this is a rimless case since the rim isn't bigger than the main body of the case. Since the rim doesn't stop it from dropping into the barrel like the revolver case (the headspace that I was talking about before), this case headspaces on the mouth of the case -- the open end that holds the bullet. It doesn't seem like anything thick enough to stop the cartridge from dropping into the barrel, but as I found out with the reloading -- this is a game where hundredths or thousandths of an inch mean the world.Headspace is the amount of free space that the cartridge has to move back and forth in the chamber. When something "headspaces" on something that something is the thing that prevents it from going further into the barrel. The other side is governed by the breechface of the gun. Typically you want a few thousandths of an inch of headspace. If there's too much then the firing pin isn't going to hit the primer properly. If there is too little (negative headspace) then the round wouldn't be able to properly chamber.

.380 ACP (9x18)

This is the only case in today's array that was designed by the great American firearms designed John Moses Browning. He set this one out in the wild in 1908 shortly after the .45 ACP was created by him.Like the Parabellum this headspaces on the mouth of the case. The intent of the design was to create a cartridge that was powerful enough to be useful, but mild enough to be able to use the simple blowback action that was easier to deal with.

.38 Super (9x23mmSR+P)

This round came about in the 20's as an upgrade to the .38 ACP round. It basically never got a whole lot of love until recently for use in competitions.The reason you use this in competition is that there's a minimum power factor you have to reach to get certain bonuses. The problem is that normally you had to use bigger cartridges like the .45 to get there. That's a tradeoff though since with the bigger (well, wider) cases you could fit fewer rounds in your race gun so you had to reload more often. That takes time.With the .38 Super you have a case with enough capacity to get a 125 grain going 1400 feet/second to make the minimum power. Of course these rounds would make a normal gun blow up... but race guns aren't normal guns. ;-)

.357 Magnum (9x31R)

In 1933 a group of folks at Smith & Wesson decided to make an even hotter .38 Special. Since there was su much extra space in the case you could fill it up the rest of the way and have a lot more power. And that's exactly what they did!There would be a problem though if the existing revolvers chambered a round that was so much more powerful -- the chamber in the cylinder was never built to handle that pressure before. The solution was to simply add on another 1/8-inch to the length and call it a day.Easy peasy!

9mm Makarov (9x18)

This was the communist re-imagining of the normal 9mm Parabellum cartridge. If anything it's a weaker brother of it. It was designed to be used in a blowback designed gun which by that fact alone required substantially reduced pressures.It's also a tiny bit bigger than the other 9mm's here to make it incompatible -- on purpose! (Think cold war conflict. If the enemy [us!] captured ammunition, you don't when them to use your own ammo on you!)

.357 Sig (9x22)

Of the bunch this is by far the newest of them. In 1994 Sig-Sauer took a .40 S&W case and necked it down to hold a 9mm bullet. The intent was really the same as moving from the .38 Special to the .357 Magnum -- more powder = more power. The additional volume in the case lets you push roughly the same bullet around 200 feet/second faster. Velocity translates into energy and the faster something goes the more punch it packs.Why the name? Even though the .357 Sig fires identically sized bullets as a 9mm Parabellum (0.355") they called if .357 to evoke the .357 Magnum. They were trying to get the same ballistics as the revolver cartridge in an auto-loader.[smugmug url="http://photos.vec.com/hack/feed.mg?Type=gallery&Data=16612528_Ro7vL&format=rss200" imagecount="100" start="1" num="100" thumbsize="Th" link="lightbox" captions="false" sort="true" window="true" smugmug="true" size="L"]