First of all, I thank you guys for taking the time out to help me figure this out.
Second. You folks sure know your stuff!
I removed "everything" from the magazine tube, including the "three shell limiter". Now I can feed five shells into the tube. I did this previously but must have developed a brain fart at the time, since I totally ignored the restricter.
Yesterday I took the M2T to the range, it worked flawlesly just like everyone on this forum says. The shoulder is a bit sore today but it'll be fine tomorrow.
Thanks again.