Do you have bigger pictures?

e-gunparts lists a forend spring that is shaped like you describe. http://www.gunpartscorp.com/catalog/...00G&catid=5498
However, from your description and what I could make out in the pictures (trigger group?), it may be the hammer spring (http://www.gunpartscorp.com/catalog/...570&catid=5498) or trigger spring (http://www.gunpartscorp.com/catalog/...280&catid=5498).