Would Domain Forwarding Hurt Your SE rank

i don't see info about this much on here, but what if i purchased a domain for the sole purpose of forwarding to a certain page on my website. for example i may own keyrings.com and forward to a page one my website which deals with keyrings.

You're talking about 301 redirecting right? It won't have any effect on rankings. The only use it would have is for capturing the few people that type it into the address bar.