I would wager that not as many are made as the other models as they are not very popular for carry & competition so a lot of places may not stock them. I've seen them around in local stores, so maybe it's just your area.

I wanted a 21SF also, because the standard model 21 was just too large for my hands. I was disappointed when I finially got to hold a 21SF. It was still too large. Putting them side by side, I could tell a difference, but it wasn't enough for me. I'll probably need to go with a single stack .45ACP to fit my hands. 1911s feel good to me.

MitchellB you might try handling some of the other polymer double stack 45's just for drill to see if they fit you better. The M&P, XD, XDm, FN, PX4, Sig 250, HK45, USP are all possibilities that have smaller or more ergonomic grips.