My guess about the trouble feeding is simply a weak spring in the tube. If yours likes short cartridges Cadd, it is probably because the spring is just not strong enough to push the long ones out that .020". Does anyone know if there is an aftermarket spring that is a little beefier? Here is another idea. Compress the spring from the top also, under the cap to shorten the spring by compressing it, thus making it stronger. I got a new follower the other day. When I get the new stainless steel follower, the original that I buffed down will go into the tube, either atop the spring for maximum compression or it will go over the spring for just a bit of a squeeze.
I noticed that the ammo will feed reliably even if there is no spring pressure pushing it. The cartridge will fall into the ramp of its own weight. When the follower on my rifle got gooped up this last range trip there was no pressure at all on the cartridges because the follower was stuck a few inches up inside the tube. I tipped the rifle with the muzzle up and the cartridge fell right in to place. But, the next one left in the tube also fell in prematurely. That was easily remedied...tilt the rifle down and let the cartridge run itself back up the tube and then cycle the shell in the feed ramp into the chamber. It was a PITA to get this thing to shoot with the stuck follower but it did work. Hopefully the stainless model will remedy the problem.
I am also going to do another sop and mop inside the tube. I think all I did when I cleaned it the first time is loosen up the glop from the factory and it flowed down to where the follower rests, causing the jam up.