Why are rifle cartridges predominantly necked down, but pistol cartridges aren't?

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2agunner

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Most of the major rifle cartridges are designed with with the case being necked down. The only pistol cartridge I can think of off the top of my head that is necked down is the SIG 357 cartridge.

I remember when the SIG 357 cartridge was first introduced, they claimed a big benefit is the reliable chambering of the round due to the shape of the necked down cartridge. I don't know if that's true or not. Maybe, bullet shape is more of a factor than cartridge shape?

Therefore, my question is: why aren't more pistol cartridges necked down compared to the rifle cartridge?
 
I'll wager a guess that since the earliest day cartridge pistols were revolvers where a necked case was problematic. Most semi auto pistols have very limited reciprocating distance to their slides, bottle neck cartridges probably aren't practical. Just my thoughts.
 
The longer barrels and stronger actions of a rifle allows the use of higher pressures (in general) and longer burn times due to the longer barrel. The bottleneck cartridge facilitates the needed volume for the greater amounts of propellants without making the cartridge too long for the action. These slower burning rifle propellants are also less energy dense so the volume issue is exacerbated by this fact.

Pistol barrels being short allow less burn time and pistol actions operating at lower pressures (in general) so they use smaller quantities of faster burning propellants. This requires far less volume for propellants. And modern fast burning propellants are very energy dense reducing volume needed even more. In fact with modern propellants you run into issues with cartridge like 38 Special and 45 Colt (that started life as black powder cartridges) that have too much volume making them inefficient with modern propellants compared to lower volume more modern cartridges.
 
Thought experiment. Don't think of a bottle-necked rifle cartridge as a large diameter case necked down to hold a smaller diameter bullet. Think of it as a straight-walled rifle case "bottled out" to get more powder behind the bullet so that you can drive it to higher velocity. That need doesn't exist with most straight-walled pistol cartridges; there is plenty of capacity in the case to drive a handgun bullet to desired velocity without having to expand the case--other than lengthening it somewhat (.44 spl to .44 mag, etc.).
 
I was going to pipe up, but mcb and Legionnaire phrased me thoughts more eloquently than I could.

And for what it's worth, a bottlenecked cartridge can feed more reliably if the gun allows it. It's simply clearing more of the round before any forces around the chamber can act to change that. It just comes down to if the gun's design allows that.
 
Go back to the black powder era. Black powder was relatively low in energy (compared to smokeless.) Nowadays, if you want more power, you enlarge the case and add more powder. But in those days they had basically reached the limit of what you could achieve with more powder, so the solution then was more bullet -- increase the caliber.

Pistol cartridges fall into the velocity parameters of black powder cartridges. To get more power, your best bet is to add more bullet. That's what was done to create the 9X19 Luger cartridge. It was originally a bottleneck case with a 7.62mm bullet and the case was necked up to a straight case with a 9mm bullet.
 
Bottleneck pistol cartridges? 7.62x25 Tok, .357 SIG, the .400 and .440 Corbon, the .22 TCM, the 5.7x28... they exist but for the most part are considered specialized. Why? The bottleneck cartridges allow increased volume of powder in proportion to bore diameter, which allows for higher velocities. However, higher velocities only really work to an extent. If you can't get velocities up around 2000 fps, then you really don't see much of an increase in wounding. This leaves penetration. Some materials favor small diameter, high velocity projectiles for penetration. The 7.62x25 and the 5.7x28 in particular were designed to penetrate light barriers, flak jackets, and body armor. This is obviously a pretty specialized niche, and usually involves sacrificing some terminal effect to gain the added penetration. For the most part, the belief is that if you can't get the projectile up past the threshold velocity for cavitation, typically about 2000 fps, then you're better off with some diameter and mass. Obviously with the amount of powder space and recoil power available in a practically sized automatic handgun, achieving this velocity requires a pretty small projectile, so again, your gains are limited by the amount of space you have to work with in handguns. It's only worth it in certain specialized roles.
 
MTMilitiaman said:
Bottleneck pistol cartridges? 7.62x25 Tok, .357 SIG, the .400 and .440 Corbon, the .22 TCM, the 5.7x28... they exist but for the most part are considered specialized. Why? The bottleneck cartridges allow increased volume of powder in proportion to bore diameter, which allows for higher velocities. However, higher velocities only really work to an extent. If you can't get velocities up around 2000 fps, then you really don't see much of an increase in wounding. This leaves penetration. Some materials favor small diameter, high velocity projectiles for penetration. The 7.62x25 and the 5.7x28 in particular were designed to penetrate light barriers, flak jackets, and body armor. This is obviously a pretty specialized niche, and usually involves sacrificing some terminal effect to gain the added penetration. For the most part, the belief is that if you can't get the projectile up past the threshold velocity for cavitation, typically about 2000 fps, then you're better off with some diameter and mass. Obviously with the amount of powder space and recoil power available in a practically sized automatic handgun, achieving this velocity requires a pretty small projectile, so again, your gains are limited by the amount of space you have to work with in handguns. Your returns are worth it unless you are trying to fill a very specific requirement that most of us don't have.
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22 jet comes to mind.
 
and from the opposite view.... .30 carbine (a straight walled case, mostly...) works very well in rifles designed to use it. Take that cartridge and fire it from a handgun and you begin to see that much of the energy is wasted (fire a Ruger .30 carbine at night or low light conditions and you'll see quite a big fireball at the muzzle - while the projectile doesn't reach it's potential in a handgun at all...).

Yes, there have been handguns designed to fire .30 carbine - but not very successful (or much fun to shoot...) while that same round in the carbine designed for it is just outstanding and was one of our primary personal weapons back in WWII..
 
The first semi-auto pistol rounds were bottlenecked. The C96 Mauser and the Luger stared with 30 caliber bullets in what later became the 9x19 parabellum.
Do not mix the 30 Mauser with the Tokerev 30 caliber, it is too hot for the C96 action.
 
A prime example of why more pistol cartridges aren’t necked like a rifles would be the latest failure the “instant back-up” made by Taurus or S&W (I can’t remember which one). You could shoot 2-3 rounds then the cylinder locked up because the brass backed up against the frame making it useless.

Now it was was a 17HMR but I hope this explains why it’s just not a good idea.
 
Bottle-necked cartridges are harder to reload and a little harder/more expensive to make. So you need a reason to use them. As others have noted, needing to get a bigger charge behind a bullet is the main reason. Generally, it's not hard to get as much powder behind a semi-auto pistol round as a shooter will want/can effective use. Very few shooters fill a 38 super or 10mm auto case with powder and say "boy, I wish I had another 5 grains worth of boiler-room." So there's no need to fatten the base of the cartridge (which will, among other things, increase cost and decrease magazine capacity) to make more room for powder. You do sometimes find revolver shooters wishing for more powder room, but bottleneck cartridges don't play well in wheel guns... bottleneck brass stretches and increases rearward bolt/breech thrust forces, which leads to binding. So revolver shooters who want more power just go to longer and longer cases. E.g., 38 S&W to 38 Spl to .357 mag to 357 max.

Rifles... well, sure, lots of people want to cram more powder behind a bullet of a given size.
 
Labguy47 said:
You could shoot 2-3 rounds then the cylinder locked up because the brass backed up against the frame making it useless.
Click to expand...
That's true, but I wonder if the OP (2agunner) didn't mean just semi-autos when they said "pistols." 2agunner did mention the 357 Sig, and to my knowledge, no company has tried to build a revolver for the 357 Sig yet.;)
 
I really enjoy my .22TCM pistol. It is a bit more trouble to reload, but it is fun to shoot and (literally) a blast at the range. I guess it's not as practical as a straight walled cartridge, but I have no complaints. Reliable, accurate, nearly 2000 fps out of a pistol, basketball sized fireball--what's not to like?
 
ATLDave said:
Bottle-necked cartridges are harder to reload and a little harder/more expensive to make. So you need a reason to use them. As others have noted, needing to get a bigger charge behind a bullet is the main reason. Generally, it's not hard to get as much powder behind a semi-auto pistol round as a shooter will want/can effective use. Very few shooters fill a 38 super or 10mm auto case with powder and say "boy, I wish I had another 5 grains worth of boiler-room." So there's no need to fatten the base of the cartridge (which will, among other things, increase cost and decrease magazine capacity) to make more room for powder. You do sometimes find revolver shooters wishing for more powder room, but bottleneck cartridges don't play well in wheel guns... bottleneck brass stretches and increases rearward bolt/breech thrust forces, which leads to binding. So revolver shooters who want more power just go to longer and longer cases. E.g., 38 S&W to 38 Spl to .357 mag to 357 max.

Rifles... well, sure, lots of people want to cram more powder behind a bullet of a given size.
Click to expand...

Many times the increase in length was to make sure that the new, higher pressure cartridge, couldn't be chambered in the old lower pressure firearm.

Case in point. When the .357 Mag was released there was no real reason to require a longer case. You could reach .357 Mag velocities with no problem with .38 Spl case volume. Same for the .44 Mag.

The longer cases of both were to insure that the higher pressure cartridge couldn't be chambered in weaker firearms.

Loading .38 Spl today you really have to select the right powder to get more than 50% case volume. If loading target loads case volume used is less than 20% in most cases.
 
True, true, but many of the highest velocities come from the slowest powders that do fill up the case. There's no doubt you can drive the same bullet harder out of a .357 case than a .38 special case with the same powder and the same pressure limit (i.e., loading 357 mag-pressures in a 38 special case).
 
Diminishing returns. Fatter cartridges are going to limit capacity, and traditional straight walled pistol cartridges yield all the range and lethality that most pistol shooters can utilize with iron sights in a combat situation.

Imagine a bottlenecked revolver cartridge. Give me a six shot N frame sized gun with cartridges necked down to 32 caliber. You could probably propel them incredibly fast, but you're still shooting a little bullet out of a big gun. I guess there might be a specialized small game hunter market for something like that, but it seems there are better options and the market would be quite small.

Seems like you'd be getting into pressures high enough to blow primers too, and lock up a cylinder. Maybe I'm wrong about that. There are a number of high pressure revolver cartridges out there that do just fine.
 
P5 Guy said:
The first semi-auto pistol rounds were bottlenecked. The C96 Mauser and the Luger stared with 30 caliber bullets in what later became the 9x19 parabellum.
Do not mix the 30 Mauser with the Tokerev 30 caliber, it is too hot for the C96 action.
Click to expand...
That's funny, my C-96 has digested thousands of Tokarev rounds, so many the barrel is shot out. This topic has been discussed many times on this forum.

This is an old myth that got started years ago and has been repeated so many times that even gun writers who should know better still repeat it. When the Russians STOLE the 7.63 Mauser round and renamed it they claimed it was their own. (They are good at this.) The Russian load during WW2 fired an 85 grain bullet at 1390 FPS out of a Tokarev. The German 7.63 Mauser round as loaded by the Germans was the same bullet at 1575 FPS out of a C-96. You tell me which one was hotter. My source for this is Small Arms of the World, by Smith and Smith. Today the 7.62X25, with modern powders can top 1600 FPS. It is not loaded to higher pressures to achieve this. There are too many older guns out there for any manufacturer to load ammo to higher pressure than it originally had. That's called a lawsuit waiting to happen.
 
Somewhere around here I still have a set of loading dies for The .38/.45 Clerke developed by a fellow named Bo Clerke introduced around 1963. The idea was to ream a .38 Super barrel in a 1911 frame and the cartridge was a necked down 45 ACP. With good 45 ACP brass you could get about 4 firings before the case necks split. The idea, like most bottleneck handgun cartridges was case capacity to push a small 357 bullet at high velocities. RCBS made the loading dies and i have no clue if anyone else manufactured the dies. A few manufacturers even made the drop in barrels for the then popular Colt 1911 frames. I think it may have been Walkalong I had some conversation with several years ago about the cartridge. The cartridge fed well from standard 45 ACP 1911 magazines. The intent was a mild to shoot target cartridge.

Ron
 
tark said:
The 38 Special was never a BP cartridge. The 38 S&W was.
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https://en.wikipedia.org/wiki/.38_Special

"The .38 Special was introduced in 1898 as an improvement over the .38 Long Colt which, as a military service cartridge, was found to have inadequate stopping power against the charges of Filipino Muslim warriors during the Philippine–American War.[9] Upon its introduction, the .38 Special was originally loaded with black powder, but the cartridge's popularity caused manufacturers to offer smokeless powder loadings within a year of its introduction."
 
Necked pistol rounds that come to mind...
FN 5.7 (expensive and proprietary)
22TCM (not much support)
25naa (almost no support)
32naa (still not much support)
256 win mag (too light, not much support)
7.62x25 (kinda lost a war or two)
357 BD (a 44 that’s not a 44)
357 sig... probably the best try of the bunch

The problem I have seen with necked pistol rounds is that they don’t typically feed well in slide guns and they bind up revolvers. In autoloaders the bullet gets into the chamber and either hangs on the shoulder or the shoulder hangs on the top of the chamber because the design lets the round “flip up”. With revolvers, the case is driven back against the blast shield and the front of the case expands under pressure to fill that void. This leaves the brass tensioned between the shoulder and the blast plate. One or two shells will typically slide along, but a cylinder full quite often is enough pressure to lock the gun up due to friction.

Short version of this is... bottlenecked pistol rounds typically try too hard. 357 sig basically works because the step is slight (38 caliber vs 40 caliber) so the hang ups are minimal, but so is the velocity gain from the bottleneck effect.
 
tark said:
The 38 Special was never a BP cartridge. The 38 S&W was.
Click to expand...
38spl was a transitional cartridge. My belief is that they developed it with intentions of being smokeless but the case design outran the powder development. There are a lot of arguments over what the first “smokeless” cartridge was, and a lot of people claim 38spl 30-30, and others. Truth is, nobody really knows because a bunch of things were developing quickly.
 
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