By John Farnam
“Bullet-jump” with light-weight revolvers, particularly those chambered for 9mm:
During a Defensive Handgun Course, a student brought a Ruger five-shot revolver, chambered in 9mm.
During an exercise, shooting factory 115gr hardball from a well-known and reputable manufacturer, a bullet jumped forward far enough to protrude from the face of the cylinder and thus prevent the cylinder from rotating normally. In fact, the bullet jumped forward far enough to physically separate from the case. This not only precluded the revolver from continuing to fire, but it also made it impossible to swing out the cylinder, so the revolver could now not be reloaded!
Tilting the revolver upward allowed the errant bullet to fall back far enough so that we could swing out the cylinder. After thus fixing the problem, discarding the entire offending cartridge, and then reloading, the same thing happened a second time a few minutes later!
To be fair, this student fired a number of rounds normally before this started happening, but her faith in her revolver was still irreparably damaged.
Back in February of 2012, I did a Quip on this very issue:
“When the revolver fires, remaining cartridges in the cylinder (yet to be fired) are subjected to significant G-forces as the pistol recoils. Sometimes, it is enough to persuade a yet-unfired bullet to migrate forward far enough to protrude from the front of the cylinder, preventing the cylinder from rotating normally, and thus preventing the revolver from firing.
Ammunition manufacturers have been familiar with this issue for a long time, and thus typically put a heavy crimp into 38Spl and 357Mg cartridges as part of the manufacturing process. That crimp usually suffices to mitigate the bullet-jump issue, even in small revolvers.
However, with the advent of small, light revolvers chambered for 9mm, the problem is, once again, rearing its ugly head, as most 9mm ammunition necessarily does not come with any kind of bullet-holding crimp.
In fact, on many boxes of currently-produced, high-performance 9mm ammunition, manufacturers have printed the warning, “NOT FOR USE IN REVOLVERS,” because they calculate bullet-jump will be a problem in some guns.”
This is the reason revolvers chambered for 9mm, although otherwise well-made and perfectly functional, do not enjoy a place on my “Recommended [Arms] List.” Some ammunition is better than others, but all 9mm rounds share this same issue, even expensive high-performance brands. The 9×19 cartridge was designed to function in autoloading pistols, not revolvers!
I’m still a fan of snubby revolvers and own several, but my recommendation, when you share my enthusiasm for them, is to stick with 38Spl. The bullet-jump issue still exists, to be sure, but to a much lesser degree, particularly when you’re shooting high-performance ammunition, like Cor-Bon’s 110 gr DPX or Speer Gold-Dot. Manufacturers ensure that these bullets are adequately crimped-in and are thus unlikely to migrate.
/John
Live Inventory Price Checker
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Federal Train & Protect .38 Special Ammunition, 50 Rounds VHP 158Gr - TP38VHP1 | Palmetto State Armory | $ 45.99 $ 33.99 |
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Federal Premium .38 Special Ammunition, 20 Rounds JHP 130Gr - P38HSD1 | Palmetto State Armory | $ 41.99 $ 29.99 |
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DoubleTap Colt Defense .38 Special Ammunition, 20 Rounds Hollow Point 110Gr - 38SP110CT | Palmetto State Armory | $ 27.99 $ 25.09 |
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Liberty 38 Special 50gr HP Civil Defense Ammunition 20rds - LA-CD-38-025 | Palmetto State Armory | $ 45.99 $ 40.99 |
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As a defensive weapons and tactics instructor John Farnam will urge you, based on your own beliefs, to make up your mind in advance as to what you would do when faced with an imminent and unlawful lethal threat. You should, of course, also decide what preparations you should make in advance, if any. Defense Training International wants to make sure that their students fully understand the physical, legal, psychological, and societal consequences of their actions or inactions.
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Bigg,
The reason this isn’t a problem in pistols, as opposed to revolvers, is that the rounds in a pistol aren’t being held captive by their rim, but are instead in a magazine that allows them to move (albeit very little) as a unit; there are no forces acting on the bullet to pull them out of the case. In fact, any recoil forces act to push the bullet further into the case as the round tries to remain still as the magazine recoils with the pistol.
Mike was right regards the Lee crimp die. It really lets you make your ammo to high end specs. I guess the old wheel guns retro fitted to 45acp didn’t generate enough recoil impulse to be a problem for the troops of WW2.
I have two fine 9mm revolvers, both Smith & Wessons. One is a seven shot and one an eight. The same bullet migration situation existed.
The solution was very simple. Buy a Lee crimp die and heavy crimp all rounds before snapping them into their full moon clips.
Situation resolved.
Your student should be using moon clips to prevent the bullets from jumping forward specifically during firing. The moon clip providing the necessary headspace. Since the 9mm cartridge does not have a cartridge case rim, the cylinder fails to secure the round specially if it gets hot.
What Is a Moon Clip?
Moon clips are devices for holding cartridges as they are loaded, fired and unloaded in a revolver. As mentioned above, the clips allow proper headspace and ejection with cartridges not originally intended for the revolver.
Good to see a useful article from John for a change! I have always wanted a 9mm revolver, either with moon clips or with an ingenious solution that eliminates the need for moon clips as one manufacturer, I believe Ruger or Charter Arms, had many years ago. Reading this article has changed my mind. Absent a pressure chart in front of me, I believe 9mm rivals or exceeds .38 Spl +P+ ammo in chamber pressure. I always thought it would be an ideal cartridge for a snubby revolver due to its shorter cartridge OAL. I always figured a properly motivated… Read more »
I have been shooting revolvers for nearly 60 years and have never had such a problem. Those revolver are 22, 22 magnum, 38s both Smith and Wesson and Colt, 357 magnums, 41 magnums and all time favorite 44 magum. All of these were barrel lengths from 3 in 6 inch. Never a problem of any kind.
I;m pleased with my never let me down revolvers unlike the frequent jamming autos.
I have a Smith & Wesson 610 that does the same thing. But since I cast boolits and roll my own, I can work around it with lighter loads or even tighter taper crimping. But it bothers me that such a nice revolver works best when it’s NOT used to its fullest potential. I’m guessing the taper crimped rounds in the pistol grip of a semi auto just don’t feel the “inertial impulse” the same rounds feel higher up and farther forward in the cylinder of a revolver. Much shorter moment arm in the magazine than in the cylinder sort… Read more »
The main reason for this happening is that Semi-auto pistols and pcc rifles (9mm, 380, 45acp, etc.) headspace off the case mouth, requiring a taper crimp, and cannot use a good roll crimp. Whereas, rimmed cartridge cases, (38spl, 357mag, 44mag, etc.) headspace off the rim, and can be roll crimped to eliminate “bullet jump”. High powered rifle cartridges should also be roll crimped most of the time, unless being shot in a single shot rifle or a bench rest match rifle. This keeps the projectile from getting pushed farther into the case neck, possibly creating an overpressure situation. Some match… Read more »
I call it bullet jump! I have 2 Charter Arms, 3” .44 Bull Dogs. One is solid SS & the other is blue steel & alloy, with a tapered barrel. The SS gun weighs 2 oz. More than the blue one. 22.78 vs 20.49.
Shooting CCI shot loads, with aluminum cases, the shot capsules jump the crimp & block cylinder rotation in the blue gun but not in the SS gun! This is the only loading that has ever done this, in the 25 plus yearsI have had these guns!
Comments are 7 years old.