I am working on a Level 1 Halfling Artificer, and I can't get the CB to equip her repeating crossbow. I have checked, rechecked, and triple checked proficiency, and tried a few different types of crossbow. I can equip a hand crossbow, but not a two-handed or repeating crossbow.
Halflings, as a Small race, are very limited in what weapons they can use. Unless a weapon has the 'Small' property (which, of the crossbows, only the Hand crossbow has, IIRC), halflings cannot use them.
.Thanks for telling me though, I was extremely frustated.