The following email blast from John Farnham is republished here with the gun guru’s blessing. Click here to visit his website Defense Training International, Inc.

“S&W, Ruger, and others are make a wide range of light, five-shot, snubby revolvers, mostly in .38 special. These light-weight revolvers make wonderful back-up pistols. I carry a S&W 340PD regularly, and I hardly know I have it on! Many other gun-carriers similarly rely on them. There’s a new trend towards making these small revolvers accept autoloading pistol calibers, specifically 9mm (e.g., the Taurus 905 revolver above). Sales are brisk! However, due to their characteristic sharp recoil, “bullet-jump” is a concern. This is especially true for pistol caliber wheelguns . . .

When a 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 an 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. They typically put a heavy crimp into .38 special and .357 magnum 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 a major issue, as most 9mm ammunition 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.

My advice: stick with .38 special in snubby revolvers. I don’t see a viable solution  to 9mm bullet-jump currently. DPX .38 special 110gr works just fine.

Whatever you’re using, test it! Load your revolver and fire three  shots, one-handed. Then, open the cylinder and check the remaining two rounds for signs of bullet-jump. Repeat the routine several times. When all unfired cartridges look normal, you’re probably okay.”


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34 Responses to Lightweight Revolvers and the Dangers of “Bullet-Jump”

  1. Friend has a S&W Model 1917 .45 acp revolver and never had this problem, but it is much larger and heavier, and really does not recoil very much.
    I would imagine the small snappies could be a problem and a lot of this is going to be ammunition dependent.

    • My S&W 625 “N” frame, 45 ACP in moon clips, also seems immune to “bullet-jump.”

      With 9mm pistols getting very small wouldn’t they encounter “bullet-jump” too? Perhaps it’s the difference in the way the hand absorbs the recoil with a little revolver tending to flip up compared to the pistol recoiling more straight into the hand.

      • .45 is a low-pressure round, so it doesn’t provide quite as sudden or violent a recoil impulse.

        You shouldn’t see this in semi-autos unless the ammo is downright defective. There’s a spring between the slide and the frame that literally acts as a shock absorber for the rounds in the magazine, spreading the jolt out in time.

        • Makes sense. Folks shooting the S&W 610 revolver, 10mm in moon clips, might have more concerns in this regard than folks shooting a 45 ACP revolver.

          Maybe this is part of why the 10mm S&W model 310, the Night Guard scandium alloy revolver, has apparently been discontinued.

      • Thousands of 45 ACP revolvers have been sold with thousands of rounds going through them with no problem. I heavy revolver with a low pressure cartridge won’t jump, not enough g force on the bullet to make it jump. An all titanium, 11 oz 357 will make nearly anything jump (including you) which is why I sold my Taurus Ultralite.

  2. Good information. I have a snubby .38 Ruger LCR and a .357 Ruger SP101 (not so small). No problems with it, but I had considered a .45 ACP revolver recently.
    I had not considered bullet jump. I will go to the range this weekend. Using a black marker, I will color where the bullet and brass come together. I will look to see if there was any movement. I don’t expect any as the .38 and .357 revolver seem to have addressed this, but I will check.

    • You will only see the problem with ammo not meant for revolvers such as 9mm, 40 etc. The lighter the gun and the faster the bullet the more it will be an issue.

      Also depends on how tight the fit is between the brass and bullet with each brand of ammo and perhaps each lot.

      Obviously, the problem will not exist constantly as those revolvers would never work. The problem is rare, but happens often enough to be concerned.

      • Uh, no. You do see it in revolver ammo too. Heavy bullet + light gun = bullet pull. And since heavier bullets have lower muzzle velocity, it’s actually the slower bullet (all else being equal) that’s going to exhibit this more. Higher pressure will also cause more of an impulse. .44 special runs at a max pressure of 15,500 PSI. .40 S&W is 35,000 PSI. That’s going to create quite a jolt.

        So if you’re going to buy one of these things – and it’s still a Taurus, so I’d advise against it – be smart and load the 135 grain reduced recoil .40s.

  3. If the bullets truly protrude further and further from the shell case, I would think binding the cylinder would be the least of your problems, considering the length of even the smaller cylinders. I would be more worried about the effects of a round discharging with the bullet practically out of the case.

  4. What would the point of a 9mm be in a snubnose?

    Being the lousy-shot rental junkie at the local range, I broke in their new 38 S&W bodyguard rental with the incredibly useless (and quickly removed by the staff) laser… I could hit the paper at 7 yards, but that was about it. I could probably defend myself better with a swiss army knife.

    I really don’t see the point of running 9mm in a gun of that size and weight: it was already nearly unusable with .38. Especially in comparison to 9mm semis like the LC9 (which was vastly easier for me to shoot)

    • Many people buy guns because they are fun. Others buy them to have compatible calibers or because they believe a particular caliber may be most effective for their needs. Others enjoy the ability to drop a loaded moon clip into a revolver. Also, the Taurus is just a tiny bit smaller than the standard model 85-maybe just enough. I personally have had a number of “j-frame” sized guns. I started with a pair of steel framed .38’s-a pair because they would “swell” when hot from firing a couple of hundred rounds and I would swap them. I then went to a lightweight, then to a titanium/scandium ultralight, later to a scandium 3 inch model. I can shoot them all accurately in .38, although I now leave the .357’s alone. I also fire a 325 in 45ACP, and may try a Rhino in .40 at some point. The thing is, we’re all different and enjoy different things.

  5. This is also referred to as “jumping the case mouth” or “bullet pull”. Even in .38s, you really want to stay away from heavy bullets. In fact, some lightweight .38s are explicitly marked “125 grain bullets only”, and I go no heavier than that regardless. The heavier bullets have more inertia, want to stay where they are as the gun recoils. The gun moves, the bullets don’t, and the next thing you know…

    If you do have a 9mm revolver, stick with 115 grain bullets. That should help minimize the issue.

    .40s are naturally going to be heavier, so I would just recommend against any kind of .40 airweight. If you like big bore revolvers, a steel .44 special is the only way to go.

    • I have an S&W marked “No bullets lighter than 120 grains.” As I understand it the lighter bullets have less contact with the inside of the case (since they are shorter) and so pull more easily. Same with guns marked “jacketed bullets only” since soft lead will pull out of a casing more easily than a jacketed bullet.

  6. “Whatever you’re using, test it! Load your revolver and fire three shots, one-handed. Then, open the cylinder and check the remaining two rounds for signs of bullet-jump. Repeat the routine several times. When all unfired cartridges look normal, you’re probably okay.”

    Absolutely correct. That is the same warning found in the manual for my Airweight (scandium) S&W .357 J-frame. They also warn you not to use any bullet lighter than 120gr.

  7. hmmmm… this has reminded me of another question about revolvers.
    A number of years ago I saw an episode of the wonderfully gun hating show CSI, and in it they had a pretty interesting malfunction.
    In the episode, a cheapo .22LR revolver was fired, but the parts were held together so loosely that a second round in the cylinder went off with the one that was supposed to go off. They called this “sympathetic discharge”
    Can anyone tell me if this is at all possible in real life?

    • Seems unlikely, since the firing pin would only hit one primer (even a rimfire “primed area”) at a time. However, if you had a REALLY cheap revolver made with the .22 rimfire rims nearly touching in adjacent chambers of the cylinder, AND the revolver was so loose and out if timing that the firing pin struck in between two loaded chambers, it MIGHT manage to hit two primed rims at once. Not being a fan of increadibly cheap pot metal revolvers, I have not been able to conduct this experiment.

      You can get a sympathetic discharge in a muzzleloading caplock revolver if you don’t put grease in the end of each chamber after loading. That’s caused by the flash of the black powder jumping into one of the other chambers, not by the “looseness” of the revolver.

    • I have seen this in real life and we diagnosed the problem. It was in an old 22 Rossi revolver. The chambers were overbored and the there was a lot of slop between the back of the cylinder and the frame. During recoil with some brands of high velocity 22, the next round in the cylinder would bouce back off of the edge of the frame (the round part that covers the back of the cylinder) with enough force to set off the primer. It was a caused by a perfect storm or problems. The 22’s had to have enough slop to move back and forth in the cylinder and gain some momentum; and the brass had to be thin enough that the bouce would dent it. But it did happen, and that gun had to go.

  8. “This is especially true for pistol caliber wheelguns”

    A revolver is a pistol. A revolver is a pistol. A revolver is a pistol.

    • According to my dictionaries, a “pistol” is a “handgun with a chamber integral to the barrel.”

      This means that single-shots (eg, a Contender), 1911’s and other semi-autos are pistols, while revolvers, harmonica handguns, etc are not.

      • pis·tol   [pis-tl]
        a short firearm intended to be held and fired with one hand.

        From, “Based on the Random House Dictionary”

      • The word “pistol” has been around since the 1500s. It can refer to any handgun. Pirates did not use autoloaders. But they did use pistols.

  9. Bullet-jump is all too real with lightweight guns and heavy bullets. I’ve had this problem with the following S&W revolvers… 310, 325, 329, and 329PD.

    Yeah, I like big bore snubbies and big booms. My night guard collection + the “plastic gun feeling” of the 329PD is all good and well and are kind of fun for having some toys… but I’d never choose to protect my life with one. Plenty of other options for that.

  10. Personally I don’t see the problem with pistol cartridges as long as the revolver can utilize this very old invention called “Moon Clips” (some call them Star Clips).

  11. I just got a Ruger LCR 9mm and tested 9 kinds of old ammo I had sitting around. All were standard pressure factory loads, but at least 5 years old. My procedure was: load 5, shoot 4 and compare the 5th to others of the same type. I was using the moon clips and doing everything the way I think you are supposed to.

    ALL NINE had issues, although none actually jumped enough to cause a jam. 8 moved enough so the cartridge was visibly longer, the 9th separated when I tried to extract — bullet stayed in the cylinder when the case came out.

    I plan to re-test with new ammo, in the hope that some manufacturers have fixed something. Have asked Ruger support if they can recommend any ammo and will hold off on buying anything while I wait for a reply. Meanwhile I’m tentatively in the “Whoops! 9mm in a light revolver is a bad idea” camp.

    PS: I have seen several forum threads linking to a Boberg list of known-good ammo,
    This list has zero credibility with me because 4 of the ammos that failed my test were on their “known-good” list.

    • David – Any updates on 9mm ammo that does work well? I recently purchase a LRC 9mm and twice have had the 5th round bullet creep out of the casing, both times I was shooting Federal 115gr purchased at Walmart. I’ve read online that Federal does seem to be more prone to crimp creep than other brands, so I will avoid it in my revolver going forward. I have read some positive feedback online that Remington UMC 115gr & Winchester White Box 115gr have preformed well any experience with either?

  12. It seems the trend towards rimless pistol rounds is mostly regarding 9mm revolvers (.45 acp revolvers obviously exist but are rarely of the lightweight construction that can lead to problems). From what I’ve heard and seen, the 9mm revolvers often are based on the .357 model, and retain its longer cylinder with the short 9mm case. Therefore, for the round to jump out far enough to bind the action the bullet would have to completely jump out of the crimp and slide all the way out the front of the cylinder. Not saying it can’t happen, but I’m not going to condemn these guns until there are more reports of it actually happening…

    • So a question: If the bullet did jump, but did not bind the action, and the jumped round went to battery and got fired, what is the worst that could happen? I imagine if the bullet didn’t unseat completely, but just spaced a little, it would still fire OK. If the bullet completely unseated, would that result in a squib, or would the bullet be like to still make it out of the barrel, perhaps with less velocity?

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