OK - I actually have a Marlin 336 lever action 35 Remington myself, and a friend of my brother who borrowed it last summer for some hog hunting actually bought some of these Leverevolution bullets, and gave it to me when he returned it. I had not really inspected what type they were until now.
I just now tried loading and cycling 5 rounds myself.
On the first rotation of the 5 rounds, the 2nd round feeding cycle gave some trouble, the 1st rounds ejection hanging up a bit as I recall.
Second rotation no real issues.
Third rotation, during the 1st round's feeding, lever down/forward in the cycle and the round feeding out of the magazine tube and into/onto the cylinder feeding mechanism, the round totally bound up a little less the halfway out of the magazine. It and the lever and lifting/feeding mechanism were jammed and would not move. Also the side port movement blocked due to the round. I had to get a screwdriver and aluminum cleaning rod and gently nudge the round back forward into the magazine using the ejection port and then the feed port. At this point I got all 5 rounds to cycle cleanly and then I called it quits.
So, it does make you wonder if there are issues with the model 336 and this cartridge design. I like its improved ballistics so would like to know what the fix/tweak might be that will make it work better in this firearm.