I have never heard of nor do I know anyone who has actually heard of a tube detonation in a .357 rifle. If anyone else has, I would be very interested in hearing a first hand account. Personally, I don't think it is possible in a .357. I regularly shoot rn lead bullets in mine but they are not jacketed.
Howdy Again
Over the years in the CAS world I have heard several accounts of ammunition being set off in the tubular magazine of a lever gun. No, I have not been there to witness it, but such incidents have been recorded on the SASS Wire. No, I cannot specifically recall such incidents with 357 mag ammo, I can recall hearing about several specifically in Uberti 1860 Henry reproduction rifles, and these rifles are only chambered for 45 Colt and 44-40 cartridges.
These incidents have usually happened when the tab of the spring loaded follower has slipped out of the grasp of the shooter when loading, allowing the magazine spring to slam the follower down on a stack of ammo in the magazine. Yes, I can recall reading of several incidences of this happening, usually causing the slot in the magazine where the follower tab rides to fold out when the rounds in the magazine went off. Sometimes the magazine could be bent back into shape with no harm to the rifle, sometimes not and the barrel/magazine assembly were ruined.
For those not familiar with the Henry rifle and its loading procedure, here are a few photos.
This is my 'Iron Framed' Henry. You can see the brass follower tab protruding below the magazine.
In this photo, the follower has been pulled all the way forward, and the barrel sleeve at the front of the barrel has been rotated to open the front of the magazine. The follower is retained by the screw, and about 1/16" of the follower is engaged in the relief between the barrel and magazine, preventing the barrel sleeve from rotating back to its normal position.
Here is the view from the muzzle, showing the opening at the front of the magazine. The magazine spring is compressed and is completely contained at this time in the barrel sleeve. The slot down the magazine that the follower tab rides in is visible in this view.
Another view of the same thing.
The problem can arise because the only thing preventing the barrel sleeve from rotating back in position is about 1/16" of the brass follower, and it would not take much effort to force the barrel sleeve back in position, over riding the captive effect of the follower against the barrel.
For this reason, when loading my Henry I always wrap my left hand completely around the barrel, below the follower, to prevent the follower from going anywhere, should something jostle me or the rifle while I am loading. If the follower were to escape and be allowed to jump down its slot, the magazine spring is under tremendous pressure and will slam the follower down on the stack of rounds in the tube with considerable force. With my hand preventing the follower from going anywhere, it will smack into my hand, and yes it does hurt, but that is better than a ruined barrel. There have also been instances reported where the shooter has carefully reloaded, then once he rotates the barrel sleeve back in position he has let go of the follower tab, allowing the follower to slam down on the stack of rounds, rather than lowering the follower onto the stack in the magazine in a controlled fashion.
Notice that in these instances, it has not been recoil from a fired round which has caused a magazine discharge, it is the force of the magazine spring. Yes, Uberti has attempted to address this situation by installing a small disk of rubber in the follower, but the rubber disk is actually useless. These magazine discharges have occurred with the piece of rubber in place.
This is why I caution that it is not recoil that may be the culprit in a magazine discharge of rounds, the magazine spring is a more likely culprit. I will admit that during normal operation of a lever gun, the magazine spring does not slam the rounds back quite so violently as the follower of a Henry gaining momentum as it accelerates down the magazine if it has been given the freedom to travel most of the way down the tube. But still, every time you work the lever of a lever gun, the magazine spring slams the entire column of rounds in the magazine back the length of one round as a round is stripped out of the magazine by the carrier. There is still considerable force operating, and I prefer to err on the side of safety and will never put anything but flat nosed bullets into one of my lever guns.