gammalt, gamla and...? I wrote down the Alternative Patterns that figure on the tips and notes, but I can't work this one out :c
gamla is often used in plural; "gamla hundar" old dogs.
and gammalt is often something used for describing like, "det är ett gammalt hus" It is an old house.
(then there's something called "gammal" which is used for singular forms. like; "min hund är gammal" my dog is old.)
While it would normally follow the pattern gammal, gammalt, gammla, I'm not sure that one is able to pronounce a double-consonant followed by another consonant, so gammla would become gamla. Don't take my word for it; I don't know if Swedish allows double vowels followed by vowels. I'm probably incorrect.
There can be 2+1, for example "kallna", to cool down. However "M" is ever only double between two vowels (and the first vowel is short, and word don't derived from "döma" (judge)), or at the end for the three exceptions "damm, lamm, ramm" (because there is also long vowel "lam, ram, dam") (pond/dam, lamb, ram, paralyzed, frame/bear-paw, lady)