How does a bullet go from cylinder to barrel?

Let's take these one at a time
1. It simply jumps the gap. In a properly timed revolver the chamber and barrel are aligned perfectly.
2. A shorter cartridge with the same diameter can be fired in a longer firing chamber. The bullet just travels a bit until it gets to the throat. It works with SAs too. IE a .380ACP (9x17mm) can be fired in a 9mm Luger (9x19mm) chamber. However the revolver is not dependent on the power of the cartridge to cycle the action and chamber the next round. A .380ACP does not have the power to cycle the action of a 9mm Luger pistol.
3. Yes, there is a minimal amount of power loss at the BC (barrel/cylinder) gap. In a properly set up revolver, this loss is so minimal that it isn't even worth concerning oneself about it.

“How does a bullet go from cylinder to barrel?” = Very carefully

Seriously, the front of the chambers of the revolver cylinder are the same diameter and the cylinder indexes so that each chamber aligns with the back end of the barrel. The back end of the barrel has a “Forcing cone” shape, kind of like a funnel, to make up for any slight misalignment and guide the bullet into the barrel as it transitions from the cylinder chamber into the barrel. Or goes from the cylinder, across the gap between the cylinder face and the entry into the barrel. The gap between the cylinder face and the barrel is generally only a few thousands of an inch. I believe most factory specs are .003 to .008.

Yes, there is a loss of gas/pressure from the gap, but it is not a significant factor unless the gap is excessive. Well, it would be significant to anyone standing alongside when the gun is fired.

There are a number of calibers that share the same diameter bullet. The difference between the calibers is generally the case length and the power of the round; 44 mag has a longer case and is more powerful than the 44 special. 44 spl can be fired in a 44 mag, but not the other way around. The same with 357 mag and 38 spl. You can shoot 38 in a 357, but not the other way around. The same applies to a number of other calibers. A 22LR gun can also use 22 long and 22 short ammo. 22 magnum is a separate bird unto itself because the diameter of the case (and the chambers in the cylinder) is a larger diameter than 22LR. That’s why 22LR/22mag revolvers have two separate cylinders.

I hope this helps.

sigsmoker said:

I wonder how a 44 mag can use a 44 spl., a 357 mag use a 38 spl. Sometimes a cylinder is changed like a 22 mag for a 22 LR cylinder, but the length of the cylinder is still the same size.

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Unlike 357 Magnum/38 Special and 44 Magnum/44 Special where the cases and bullets are identical except the Special case lengths are a little shorter than the Magnum, with 22 long rifle and 22 magnum there are more differences in dimensions of the case requiring a different chamber. The 22 magnum case is not just a longer case as with 22 Short/22 long rifle cases.

In 22 RF convertible revolvers, the cylinders are the same length because they have to fill the space between the breech and the barrel in the revolver.

Hope this helps.

sometimes a gap with a lot of daylight

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Then the gun should be replaced

a .380ACP (9x17mm) can be fired in a 9mm Luger (9x19mm) chamber

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No! No! No! This is not true. Attempting to do so could result in an unsafe condition! Semiauto cartridges like these index on the case's mouth. A .380 ACP is way to short to properly seat in the chamber of a 9mm Luger. Trying to shoot a .380 ACP in a 9mm Luger firearm could cause serious damage to the gun, the shooter, and anyone standing near by. Furthermore, 9mm cases and .380 cases are very different in terms of diameters, length, and tapper. For example: you can't use .380 reloading dies to load 9mm, or visa versa. You cant use 9mm brass to make .380 brass.

Revolver cartridge combinations like .32 S&W/.32 H&R/.327Mag, .38 Spl/.357 Mag, and .44 Spl/.44 Mag index on the rim at the base of the cartridge. The only difference between cases is length. The rim and all other dimensions are identical. You can use .38 Spl reloading dies to form and load .357 Mag. You can shorten .44 Mag cases to make .44 Spl cases. You can safely shoot a .32 H&R is a firearm chambered for .327 Mag.

While the book says that the 9mm, 380 acp and the like, all headspace on the case mouth....the truth is that the extraxter holds the case against the breach face, no matter how short the case. In reality, the case mouth of auto cartridges rarely ever touch the barrel stop.

As far as the diameter difference of the 380 vs the 9mm...it's true but again, reality shows that brass cases have enough elasticity to absorb the difference and just bulge a bit. Is it ideal? No, but that's what happens.

There was a revolver called a Medusa that could fire 357, 38, 9mm, 380, 38 super, just about any 35 caliber. It had a unique method of holding the cartridges to keep the smaller ones from falling down into the chamber.

The "barrel jump" of a revolver happens in almost all guns. In a rifle, it's called "free bore". There is always a portion of the bullets path where it is in free flight before it hits the rifling.

There is always a portion of the bullets path where it is in free flight before it hits the rifling.

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Excepting of course those bench rest, and some long range shooters, that "soft seat" into the lands.

/Bryan

In a revolver the forcing cone and the amount of rotational free play when the cylinder is indexed and locked are very important. On many guns the bullet jumps the BC gap and must "self align" with the bore. That's where you need a tiny amount of play so the cylinder can come into alignment with the bore. If a revolver is built so that the cylinder is "line bored" with the barrel then cylinder alignment is dead on and the bullet has a straight shot in. Unfortunately line boring is pretty much only seen in custom revolversmith's work.

Lucky Derby said:

Let's take these one at a time
1. It simply jumps the gap. In a properly timed revolver the chamber and barrel are aligned perfectly.
2. A shorter cartridge with the same diameter can be fired in a longer firing chamber. The bullet just travels a bit until it gets to the throat. It works with SAs too. IE a .380ACP (9x17mm) can be fired in a 9mm Luger (9x19mm) chamber. However the revolver is not dependent on the power of the cartridge to cycle the action and chamber the next round. A .380ACP does not have the power to cycle the action of a 9mm Luger pistol.
3. Yes, there is a minimal amount of power loss at the BC (barrel/cylinder) gap. In a properly set up revolver, this loss is so minimal that it isn't even worth concerning oneself about it.

Click to expand...

Say WHAT now?
You don't' mix the grain with the grape.
You don't put gas in a diesel.
You don't put fruit in beer.

^^

I agree, but it can be done. I think there's even a guy that shot a 223 out of a 9mm Glock for a YouTube video...

The point is, don't be telling people it CAN be done, BECAUSE IT IS DANGEROUS!

Sigsmoker - if you're not already, please be aware of the dangers of gases blasting out of that cylinder/barrel gap. They're very real.

You probably shouldn't but you can fire .380 in a 9mm. As stated, it probably won't cycle and will bulge the case. If you are on this forum then you've got the tools to see it for yourself. A quick trip to YouTube will be all you need.

I'm surprised we have gotten in this far and no one has mentioned the crud rings that occur when a larger amount of "Special" length ammo is shot in Magnum revolvers.

Sigsmoker, if you read around you'll come across stories and threads on how to clean away the built up ring of fouling that occurs in the chambers just behind the throat when a lot of Specials are shot in Magnum cylinders. This is because the shorter Special length cases leave a roughly 0.1 portion of the chamber open. When the bullet jumps from the casing across this gap and into the throat at the front of the chamber the fouling tends to stick and build up. After some dozens to a couple of hundred rounds a hard crusty ring builds and you won't be able to correctly seat a magnum length round.

But this also means that if the riding band on the bullet is not long enough it can leave the mouth of the casing before it's riding the walls of the throat. At that point pressure might leak around the bullet for a microsecond or two. And it MIGHT cause some slight drop in accuracy if the gap is long enough. For example shooting a .45Colt round in a S&W .460Magnum chamber where the difference in the casings is whopping great .515 inch. In that case there is no doubt at all that the bullet will be flying for some time with no guidance and no spin. At least with .38 and .357Mag the difference is only just over 0.13. And most bullets have a longer riding band than that. So the bullet is into the throat before it leaves the casing mouth.

In a lot of situations, the bullet is going to be in the forcing cone, throat, and case neck all at once. It isn't always the case as it depends on bullet length/shape and cylinder length though.

sigsmoker, I think what you're seeing is what's called the "throat". The cylinder's ID steps down a little to better accommodate the bullet.

Kernel, I really like the illustration showing the chamber throats in the cylinder chambers, the forcing cone and the barrel though it is trying to show reasons for leading and isn't to scale.

The chamber throat is sized slightly smaller than the bullet diameter. If you have a bullet for reloading they will not simply drop through the cylinder but need to be forced through the chamber throat, this usually would seal the gas behind the bullet if the bullet is of proper diameter.

The forcing cone or as labeled in the illustration "barrel throat" guides the bullet into the center of the barrel and makes up for any slight alignment issues between the chamber and the barrel. Note the bullet is long enough that it will for a very short time be in the cylinder throat and the barrel bridging the cylinder gap at the same time.

With the mag chambering the distance between the "special" and the "mag" cartridge is only .061" in the .38 vs the .357 cases. Unless one is using a light and short for caliber bullet the small offset of the special round doesn't cause a real problem since the bullet should still be entering the chamber throat before leaving the case.

Many years ago I once did accidentally fire some experimental .380 reloads in an Astra 600 automatic pistol. Gun functioned fine, but with very soft recoil. .380 case as expected were badly bulged due to the tapered 9mm luger chamber. The .380 were loaded with a 125 grain cast bullet over a very small charge of shotgun powder.

Bottom line is.

Regardless of how it works, it does.

And has since 1835.
Or the 1500's, depending on how far back you want to go in firearms history.

rc

"How does a bullet get from cylinder to barrel?"

Where in the world else can it go? I mean really.

The design & condition of the revolver has little to do with the bullet getting "hung up between cylinder and barrel".
For all practical purposes, the only condition issue there lies in having the chamber being fired locked in line with the forcing cone. The gun has no material further affect on a bullet passing through the gap as far as getting "hung up" goes.

BC gap does affect other areas, as mentioned, but won't in itself affect the bullet's ability to jump that gap from cylinder to barrel.

Any bullet getting hung up halfway would be an ammunition function during firing, if a squib load had only enough power to push a bullet out of the case but not enough to propel it beyond the forcing cone.
This is very rare.

Denis