I'm not sure if this'll help, but I bored my A2 out to accept RCR123s. I got 3/8" and 1/2" dowels, along with various grits of emery cloth, from the hardware store. Just cut 8" or so off one of the dowels, then slot the top. Take a strip of emery cloth and feed it into the slot, then wrap the emery cloth around the dowel a time or two. Voila! you are now ready to get blisters everywhere from slowly sanding out the inside of the tube. If you need help visualizing it, just look at guitar tuners. There's probably an easier way to do this, if you're in a hurry. Oh yeah, I'm not sure if this applies to the L1, but I stuffed a piece of toilet paper down the tube of the A2 before I started sanding, so none of the sandings got in its brain.
-Winston