Revolver question

[Brians356]

I know relatively about the finer points of revolvers. In a revolver, I gather, the bullet leaves the case mouth, and some time later engages the forcing cone and then enters the bore. After the bullet clears the case mouth, hot gases escape and bleed out the cylinder gap. My question is this: How far, minimally, will the bullet "jump" unsupported before contacting the forcing cone?

Alternatively, is it possible for the bullet to engage the forcing cone, or even enter the bore, before the bullet clears the case mouth?
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[jackieschmidt]

I know a lot about revolvers. I come from an era when the semi autos were of two classes. The 1911, and everything else. We shot revolvers.

If you are shooting a 44 magnum, and are using the lighter, and shorter 180 grn hollow points, the bullet is way out of the case before it engages the lands. However, if you are shooting big 260 grn hard cast semi wadcutters, it might still be a tad in the case when the bullet engages the lands.

here is a Sierra 210 grn hollow point in the lands in one of my Model 29 Smiths. As you can see, it cleared the case considerably. My Rugar Super Black Hawk is the same.

Keep in mind, on quality pistols, the forward end of the cylinder does have minimum clearance over the bullet. There is gas leakage, but then that’s the nature of the beast.

 

[Brians356]

Jackie, thanks, that's very informative. The reason I ask: I watched one of Chris Baker's videos over at LuckyGunner, which looked into "Does handgun recoil begin before the bullet leaves the barrel?"

The video (below) uses a high-speed motion camera to observe whether the gun moves before the bullet exits the bore. In two different autoloaders, there is no observed recoil before bullet exit. In a 357 revolver, recoil always starts before bullet exit.

My theory as to why: Well before exiting the revolver barrel, the bullet exits the case mouth. Significant gases are vented from the cylinder gap as the bullet leaves the case. Just as a bullet (and gases) exiting a barrel creates a recoil impetus, so does a bullet exiting the case. Only a portion of the gases escape through the narrow cylinder gap, as a lot of it is seen escaping the muzzle behind the bullet as well. Nevertheless, the slow motion video shows clearly that the revolver recoils as soon as gas escapes the case through the cylinder gap.

And why not? Think about an old "pepperbox" revolver like the Allen, which had a rotating cylinder/barrel, like a Gatling gun. If you took a modern revolver and removed the barrel from the frame, you'd be left with something similar. Obviously firing bullets from just the remaining cylinder holes will create significant recoil. But in a regular revolver, the bullet soon engages the forcing cone and bore, which it seems to me would decelerate the bullet and start to dampen the initial recoil. Too complicated for me to analyze, and beyond the scope of this post.

Am I far wrong in my reasoning for why a revolver recoils before the bullet leaves the barrel?

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[AccelR8]

This is true but it’s not quite as bad as it might seem. The SAAMI spec for the 44 Magnum chamber mouth is .4325” diameter meaning that the chamber in the cylinder tapers down rather abruptly after the case body to a straight section of .4325” where the bullet travels through as it leaves the case mouth and before leaving the cylinder. The SAAMI spec for a lead bullet is .4320” so the bullet is not as unsupported as one might think as it enters the forcing cone and rifling. You could almost think of it like the free bore in a rifle chamber.

For example, to use a rifle chambering of similar bore size, the 416 Weatherby SAAMI spec is a free bore of .4165” and a bullet of .4160.” So both the 416 Weatherby rifle chamber and the 44 Magnum pistol chamber have a “free bore” half a thousandth larger than the bullet, at least according to SAAMI specs.

Of course what the manufacturers actually build 'em to might be a different story!

edit to add, I wrote this reply before the last post so that's not what I was replying to, the recoil aspect of it. I was thinking more of an accuracy thing

 

[DirtySteve]

I try not to hurt my head thinking too much. All I know is I have a S&W M19 that will put 6 DEWC touching at 25 yards. I don't care how it happens as long as it does.. lol

 

[JSH]

In my old FA 357, custom LBT mold bullet nose is just bellow flush with the cylinder, weight depends on alloy.
A compressed load of H110 sparked by SRP does the trick. Yes it is in the forcing cone and in the throat. This rig has been through two of my mentors from years gone by, if it is an “O” on the score card it is operator error. 10 shot groups @200 just under 6” is fairly common, iron sighted, a bit better with scope and not far off of some single shot rigs.

 

[divingin]

In a semi-auto pistol, the initial effect of recoil is to start the slide moving back. Next is possibly unlocking the barrel and extracting the case. Recoil of the pistol doesn't occur until the spring compression is enough to affect the frame. Hence the generally softer feeling of semi-auto felt recoil vs a revolver, where the instant recoil starts it's affecting the grip.

 

[Brians356]

In a semi-auto pistol, the initial effect of recoil is to start the slide moving back. Next is possibly unlocking the barrel and extracting the case. Recoil of the pistol doesn't occur until the spring compression is enough to affect the frame. Hence the generally softer feeling of semi-auto felt recoil vs a revolver, where the instant recoil starts it's affecting the grip.

That's true. Of course the point in question in the video was whether the barrel starts recoiling before the bullet clears it (elevating POI.) Autoloader: No. Revolver: Yes.
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[divingin]

Muzzle rise: The amount of rise is affected by where the centerline of the barrel falls in relation to where the axis of resistance from the grip is, in addition to the recoil impulse above. Most handguns put the barrel centerline at least somewhat (sometimes quite a bit) above the web of the strong hand when gripped normally. (As an aside, International Pistol rules state that *has* to be the case for a pistol to be used in competition.)

Which is why the trend of things like the Chiappa Rhino and that weird European autoloader (don't remember what it's called; only shot it once) put the bore axis well below the web of the strong hand (If you haven't seen them, the Rhino looks like a normal revolver, but fires from the bottom cylinder. The euro pistol is kind of similar, barrel is very low.) The recoil on these guns is different - very much straight back, with the muzzle rise being mostly how your wrist breaks with the shot.