I actuality haven't studied the lever rifle info lately. About 10 years ago I had success with 44 mag & taper crimped plinkers ...
Please don't misunderstand what I'm saying, its not that a taper crimp (and uncannelured bullets) won't work in certain circumstances, its that there are circumstances where the taper crimp is not enough and a proper roll crimp, is.
In a tube magazine rifle, the situation is unlike other action designs. The entire weight of the column of rounds in the tube pushed against the bullet of the last round in the tube, under the tension of the magazine spring.
Under recoil, the entire column of rounds "shifts" due to inertia (rifle recoils back, ammo stays in place, giving the effect of it moving "forward", THEN the spring slams the whole column back against the cartridge stops. The greater the recoil, the larger the effect is.
ALSO, just regular operation cycling the gun does it, too. The entire column is shoved back by the spring driving the last round in the tube onto the lifter, where the round gets a sudden stop.
I believe that a bullet with a crimp groove, and the case rolled into that groove provides greater resistance to the bullet moving (forward or back) than a taper crimp where the case is just squeezed against the bullet.
It is always needed? No. But there are times when it is, and when it is needed, a taper crimp isn't enough.
I'd think that light plinker loads don't generate enough recoil to reach the point where a proper taper crimp isn't enough. Heavy loads, generating much more recoil COULD be a different matter.
Assuming proper bullet fit in the case, it is recoil, in certain gun designs that makes crimp necessary. (crimp is also needed for proper ignition of certain slow powders, but that's a different matter).
As an experiment, I loaded some .38s (158gr @ 850fps) without crimp. Fired them out of an N frame, no bullet movement. Fired out of a K frame, slight bullet movement. Fired from a J frame, significant bullet movement. Same ammo in three different weight guns. The gun with the lightest weight (and therefore the most recoil movement) had the most bullet jump.
A light crimp on the same rounds prevented bullet movement in all the guns used.
As to Lee dies, I will admit, I don't like them. Its not because they don't work, tis because I don't like their features. They have plastic where I want steel, rubber friction rings where I want a lock ring, things like that.
Nearly all of my 30+ die sets are either Lyman or RCBS, though I do have a couple Lee sets. I got a Lee set for .32acp, because at the time it was the only one available. I used it successfully, but retired it when I got an RCBS set. I got a Lee set for .357 in a trade, didn't like the "large step" the sizer die left at the base of the case, and have only used the seater die rarely for seating RN bullets, to avoid having to change the seater stem of my Lyman die (which is for SWC). They work, they just are, and do things I don't much like. Totally a personal opinion and not a slur against LEE.
I am VERY happy with some of the LEE hand tools, especially their decapper punch set. Its virtually indestructible, and if, somehow you do manage to break it, LEE will give you another.