Howdy
I shoot a lot of CAS. I have six rifles chambered for 44-40 or 38-40. I do not load down my rounds as many do in CAS, I only shoot rounds loaded with a full case of Black Powder, so the recoil is as robust as it will be with a 24" barreled lever gun.
Regarding the question of possible ignition of rounds in the magazine, with most tubular feed rifles there are two forces at work. When the rifle fires and moves backward in recoil, all the rounds in the magazine go backwards with it. Then when the rifle stops moving, all the rounds in the magazine come to a stop. However the rearward motion of the rifle is not an abrupt stop because the shooter's body, which is relatively soft, cushions the blow. This means the column of rounds in the magazine does not experience the kind of sharp impact that might be likely to fire a primer. Of course with a heavier recoiling round such as 38-55 or 45-70, the force will be greater, but not so much with the rounds commonly used in CAS.
The other force is the slamming back of the column of cartridges that happens every time the carrier strips a round out of the magazine when the lever is operated. This force is actually stronger than the force of recoil, particularly when the first few rounds are fired, because the magazine spring is under a great deal of compression.
It has been standard practice for a long time now in CAS to use flat nosed bullets in our rifles, we do not even use regular round nosed bullets. With flat nosed bullets, I have never heard of an instance of a magazine discharge from recoil or from the magazine spring. Even with a high primer, the meplat of a flat nosed bullet is larger in diameter than the primer, so there is nothing sharp or pointed to dent a primer enough to ignite it.
Notice I qualified my first statement by saying 'most tubular feed rifles'. The 1860 Henry rifle is a different story.
Both the Uberti replica of the 1860 Henry and the one currently being made by the Henry Repeating Arms Company load the same way the original Henry rifle loaded. The King's Patent side loading gate had not yet been invented when these rifles were made. Instead, there is a slot running the entire length of the magazine. The follower has a tab that protrudes through the slot. In order to load, one grabs the tab and pulls it all the way forward, compressing the magazine spring in the process. The last 1/16" or so of motion of the tab unlocks the barrel sleeve assembly at the front of the barrel. The shooter then rotates the sleeve assembly out of the way, exposing the end of the magazine for loading. The follower is held captive in the sleeve, with the magazine spring fully compressed.
After loading the magazine, one has to be very careful to control the follower because the magazine spring is fully compressed. If one were to swivel the barrel sleeve assembly back in position without controlling the follower, the follower would slam down on the column of rounds in the magazine with great force. This is much more force than the column of rounds sees in either of the examples I gave earlier. In fact, the fewer rounds in the magazine, the faster the follower will be moving when it strikes the first cartridge.
Everyone who has one of these rifles knows they MUST control the follower when loading the rifle. My loading procedure is to wrap one hand around the barrel and magazine just below the end of the magazine. That way, if the follower should slip out of my grasp, the tab will strike my hand, arresting its motion. Yes, it hurts, but it is better than rounds going off in the magazine. I also never drop rounds straight down the magazine, instead I tilt the gun slightly from horizontal and allow the rounds to slowly trickle down the tube.
Yes, there have been instances of rounds going off in the magazine of the 1860 Henry when slammed by a loose follower. And believe it or not, this has happened even when primers have been properly seated below flush.
As I said in the earlier post on the other page, I believe there is something else going on here. I have a strong suspicion that the force exerted by a loose follower slamming rounds in the magazine is so great that perhaps the primer cup is moving enough to pinch the priming material between it and the anvil enough to ignite a primer. I have no proof of this, but it is my suspicion. Even with flat nosed bullets and properly seated primers.