Howdy
Pay attention because there is going to be a quiz.
When metallic cartridges were first developed around the middle of the 19th Century, most of them used what is called a Heeled Bullet. The outside diameter of the bullet was the same as the outside diameter of the brass.
Cartridge brass generally runs around .010 thick or so at the case mouth, the part where the bullet is inserted. The rear of the bullet was slightly narrower so it could be inserted into the brass case. So those early bullets had to be about .020 smaller in diameter at the rear in order to be inserted into the brass case. The narrower portion at the rear of the bullet was called the heel.
The only common cartridge still manufactured with heeled bullets today are the 22 Rimfire cartridges, 22 Short, 22 Long, and 22 Long Rifle.
In this photo, a 22 Short, 22 Long, and 22 Long Rifle cartridge have been cut down the middle. If you look carefully you can see the narrower heel of each bullet inside each case.
Bullets are what is called an interference fit inside a rifled barrel. They are actually ever so slightly larger in diameter than the groove diameter of the barrel. The bullet squeezes down slightly as it goes through the barrel so the rifling can dig in and get a good grip on the bullet. This is so the rifling can give the bullet a good spin to stabilize it in flight. Bullets need to be lubricated so friction does not cause enough heat to begin to melt the lead. They need to carry some sort of wax or grease on the outer diameter where the rifling engages the bullet.
The problem with heeled bullets was the lubrication was applied directly to the outside of the bullet. In those days, ammunition was loaded with Black Powder, and the bullet lube was soft and gooey. If cartridges were kept loose in a pocket, or rolling around in a drawer, the soft lube tended to pick up lint and contamination.
This is a photo of some old 44 caliber cartridges. From left to right they are 44 S&W American, 3 44 Russian cartridges, 44 Special and 44 Magnum. Notice the one on the far left, the 44 S&W American. It uses a heeled bullet. You can see a lube groove just above the case mouth, but most of the lube has dried out by now. Notice the bullet is the same diameter as the brass case. The next cartridge, the 44 Russian, was the first cartridge where the entire bullet was the same diameter as the
inside of the brass case. The Russian government had a contract with Smith and Wesson to supply thousands of revolvers. But the Russians specified they did not want an outside lubricated bullet. By making the bullet the same diameter as the
inside of the brass case, bullet lube could be applied to grooves on the diameter of the bullet, but the grooves and their lube would be
inside the case. All five cartridges on the right of the photo have bullets whose outside diameter is the same as the inside diameter of the brass case. Look carefully and you will see there is a noticeable difference between the diameters of brass cases and the diameters of the bullets. Notice too the 44 Magnum cartridge is considerably longer than the 44 Special cartridge. Are you starting to get the idea?
The 38 Special cartridge was developed by Smith and Wesson in 1898. It always had an inside lubricated bullet that was .357 in diameter. The case was about .375 in diameter, so it was called the 38 Special, because of the case diameter. (Small aside: there is absolutely no standard system of nomenclature for cartridges. Whoever develops it gets to call it what ever he likes.)
The chambers (the part of the cylinder where you put the cartridges) was wide enough for the brass to slide in nicely. But at the front of the chamber, where the bullet would rest before being fired, the chamber was narrower, just slightly larger than the bullet. This narrow section of the chamber is called the chamber throat. It is a common feature to most modern firearms.
By the time of the Roaring Twenties and automobile equipped gangsters, police started complaining that their standard 38 Special ammunition did not have enough power to punch through a car body and disable the gangsters inside. Forget the bit about going through the engine block, that is mostly myth.
So in 1930 Smith and Wesson came out with a much more powerful 38 Special cartridge. So powerful that it would probably have blown up the cylinders in the standard 38 Special revolvers of the day.
The standard 38 Special revolvers had been built on a frame called the K frame. This was the perfect size for a six shot revolver chambered for the 38 Special cartridge. But the engineers at S&W were afraid if they put the new high velocity police round in a standard K frame Smith they might blow up the cylinder. S&W was building larger revolvers at this time, mostly 44 caliber revolvers, with a bigger cylinder in bigger frame, called the N frame. So it made perfect sense to build a new 38 Special revolver on the larger N frame and chamber it for 38 Special. The bigger cylinder would leave more metal between chambers than the smaller K frame cylinder would.
Like this. A K frame Model 19 on the left, a N frame Model 27 on the right. Notice how much more metal there is between chambers in the cylinder on the right.
The new revolver was made in two versions, one with fixed sights and one with adjustable sights. The fixed sight version was called the 38/44 Heavy Duty, the adjustable sight version was called the 38/44 Outdoorsman. 38/44 meant they were 38 caliber revolvers built on the N frame, which was usually reserved for 44 caliber cartridges.
This is a 38/44 Outdoorsman. Notice the marking on the barrel says 38 Special. Yeah, it says 38 S&W Special, because S&W liked to rub it in that they had developed the cartridge. Other companies simply marked their barrels 38 Special. Two different names for the same cartridge. What did I say about nomenclature? Sorry I don't have a comparison photo to show how much bigger the 38/44 is than a standard 38 Special revolver, you will have to trust me when I say it is.
What does all this have to do with what the lady in the gun shop was trying to explain to you? S&W was concerned that somebody might accidentally slip the high powered 38 Special ammo into a standard 38 Special revolver, and blow it up. So in 1935 they lengthened the cartridge case by about 1/10" and gave the new cartridge the name 357 Magnum. Confusing huh? Same .357 diameter bullet. The case was the same, except about 1/10" longer. A new revolver was made in 1935, specifically for the new 357 Magnum Cartridge. Based on the earlier 38/44 Outdoorsman, the chief difference was the holes in the cylinder where the cartridge case sits were bored about 1/10" longer than the holes in a standard 38 Special cylinder. The cylinder and frame were still big and strong enough for the new 357 Magnum cartridge. Shorter standard 38 Special ammunition could also be fired in it, because the bullet would simply sit in the wider part of the chamber.
The new revolver was called...........wait for it.........The 357 Magnum.
One more photo. Left to right, the cartridges in this photo are 38 Smith and Wesson, 38 Long Colt, 38 Special, and 357 Magnum. The 38 S&W cartridge is an older cartridge, and it will not fit properly in a 38 Special or 357 Magnum chamber. The 38 Long Colt is an old Black Powder cartridge with a heeled bullet. But for our purposes, the 38 Special and the 357 Magnum cartridge clearly show how the chamber for the 357 Magnum had to be longer than the 38 Special cartridge. And this photo should also demonstrate why a 357 Magnum cartridge cannot be fully seated in a standard 38 Special revolver.
OK, bonus points question on the quiz.
Why was the name Magnum chosen for the new cartridge and revolver?
