Serf's parma.... It's been a long time since I played a bjornaer. If one wants to transform into their heartbeast with clothes and/or equipment intact, what are the rules? Is there a spell? I seem to remember something from 4th edition....
Enchanted clothing or equipment of a Bjornaer might follow GotF p.96 Falke's Talisman: Perceive the Change detects the change to heartbeast, and linked Mu effects transform the item into a shape wearable by the heartbeast, or even merge it with the heartbeast.
Most Bjornaer will not carry valuable mundane equipment and clothes. CrAn and CrHe spells to create simple clothing when needed can be learned or sponted.
Formulaic or spont Mu spells can be cast in heartbeast form to transform valuable clothes. The very useful HoH:MC p.38 Minor Supernatural Virtue Unbound Tongue helps here too. Mu spells to do the same with metal armor and equipment are far harder, and few Bjornaer will bother.
Note, that melding things into your body might not feel kosher to many Bjornaer:
Note also, that there may be trouble with the Durations of many such Mu spells.
In warm climates, CrIm and/or MuIm can be even easier.