This is a very atypical Rifle climb in that it's both short and follows a fairly monolithic face (as opposed to the usual blocky stuff). The climbing is fingery and sequential, with two distinct bouldery cruxes separated by a good jug. There is a hard clip up high that some people either skip or put long draws on. The air is clean -- it's just a long drop.
Cantina Boy is on the left side of the Sapper Cave and shares a common first two bolts with Hand Me the Canteen Boy, the arching pod system/crack feature in the center of the cave. After the second bolt move into a faint dihedral (very overhanging) and up to the lip of a small roof. Thin, cryptic climbing awaits you on the light grey face above. An easier corner takes you to the anchors.
Felt every bit of .13b to me - some really hard and sequential moves at the crux. One involves grabbing an undercling which is about the same size as a potato chip. Another bonus - this cave is usually not crowded at all. Get on it!!!