310/300 Rook aka .305 Rook aka .300 Rook Special

I hope that I am OK putting this here as well as in the General Discussion forum, as I am looking for some pretty obscure info.

I am looking for dimensions or any info I can get on this cartridge, specifically if it uses a heeled bullet.

Here is the thread in GD for a better explanation:
http://forums.gunbroker.com/topic.asp?TOPIC_ID=540519

Thanks