I found one, after much searching, and used it last week-end. The 7/16 size fits the 22mm collegen casings well, where the 1/2 tapered one that came with the LEM was just a mite too big for the casings (at least in my in-experience).http://www.texastastes.com/stuffertubes1.htm(Item #700138)
It was the only one that I saw that specifically said that it fit the LEM 5 lb. The tube was pretty expensive (I thought), but my thought is always get the right tool for the job, and you are always better off.
One more thing, it's long, and it's hard to clean, so buy yourself a small bottle brush that will fit all the way thru it. I need to find one myself. I used a small diameter wooden dowel, but I need something better.
-=- Jerry -=-