Are they only snug across the vamp? not too short? as mdubs mentioned probably not a good idea however if the length is fine at least CXL is probably the leather that will stretch the most I have found. I would put a few gym socks on a shoe tree and leave that over night then add another sock the next night - I did this with my CXL indies and it worked. Also wear the hell out of them - wearing something once a month is not going to get it done.
Totally agree... if the length is good, I almost guarantee the leather will stretch appropriately. Slightly snug Chrmxl out of the box = perfect after a few wears. I too wear 10D and my chrmxl longwings are both too loose now. I have to wear thick socks to fill the space.