I realize the actual warning language doesn't list all-lead bullet ammunition specifically, but when I've asked someone from the factory, as well as an armorer instructor, I've been told that factory testing has shown that it’s the all-lead bullet ammunition which can be involved in bullet jump issues. The reason given? Well, cases crimp down and hold more firmly on jacketed bullets than they often do on all-lead bullets.
That may not be an absolute answer, though, because there's still the shooter to consider in the matter.
I remember calling and talking to someone at the factory one day and the subject of 'bullet jump' in Airlite revolvers came up during the conversation. It seems they had just received a new Sc .357 J-frame back for a reported warranty complaint. The new owner reported that he was experiencing bullet-jump with one of the major brands of 158gr JHP .357 Magnum ammunition.
Well, I was told that as it happened, the factory was able to duplicate the condition using similar ammunition ... but only when the test-shooter really, really relaxed their grip and wrist and allowed the gun to really move a lot during recoil.
The conclusion?
Apparently, when these ultra lightweight little Magnum revolvers are involved and heavy recoiling Magnum ammunition is being used, it might be possible for a heavy bullet to jump its crimp if the shooter doesn't use at least a reasonably proper and firm grip. Think of it as the lightweight little gun moving backward faster than the designers envisioned, with the bullet wanting to remain stationary in place, and the cartridge case in the cylinder jumps backward away from the bullet fast enough to overcome the pressure of the crimp.
Moral of the story? Hang onto the little beasts when shooting heavy recoiling Magnum ammunition.
Apparently, nobody ever 'limp-wristed' the Airlite Magnums during factory testing.
Now, please don't anyone get upset about this second-hand conversation about bullet jump shooting .357 Magnum ammunition, because this was apparently the first time anyone back at the factory had heard about this specific occurrence, let alone duplicate it ... and in order to do so they had to grip the gun very, very loosely. More loosely than they had ever expected anyone to grip a gun, especially such a hard recoiling gun as an ultra lightweight .357 Magnum.
These very small, very lightweight guns being chambered in .357 Magnum has got to be out there at the ragged edge of what technology and human endurance can withstand. I mean, I never expected to be able to shoot full power .357 Magnum ammunition in a platform so small and light that I could forget which pocket the gun was in, you know?
I have a Ruger SP-101 chambered in .357 Magnum. Heavy duty, robust little Magnum revolver. Remember when they were originally chambered in .38 Special, though?
Now, since I used to do a lot of shooting with Magnum ammunition in mine, I sent it out and had it Quad Ported a number of years ago. Makes shooting the gun for extended range sessions a lot easier. When I'm shooting full power 125gr, 140gr & 145gr Magnum ammunition the recoil is very controllable, and the muzzle whip is minimal. I can keep the front sight on targets at reasonable defensive ranges (3-10 yds) just about as fast as I can cycle the DAO trigger.
However, when I switch to heavier bullet ammunition, such as 158gr JHP Magnum loads, there's a noticeable (to me) increase in felt recoil back into the palm of my hand. The muzzle rise & whip is still minimal, but it starts kicking back into my hand harder. I can feel a real difference after shooting a couple of boxes of Magnum ammunition, depending on whether it's a lightweight or heavyweight bullet load.
Now, all of the Airlite J-frame Magnum shooting I've done has been with full power 125gr JHP ammunition. Lots of muzzle blast, muzzle whip and hand hammering. Fun.
So to speak ...
Since I can feel the difference when shooting 158gr JHP Magnum loads through my SP-101, compared to 125gr loads ... and the Ruger is a much heavier gun than the S&W Airlite J-frames ... I can imagine how I might experience more felt recoil impulse when shooting the same 158gr Magnum loads through an Airlite. I'll have to try it and see.
JoeG52, can you tell any difference when shooting different bullet weight full power Magnum loads in your Sc 340 with the titanium cylinder?