Hand Cannons and Forearm Mountings

By Clockwork Marvel, in Dark Heresy Rules Questions

I was thinking about a character concept, and couldn't find anything anywhere on how the two interact. The Forearm Mounting says that it keeps the user's hands free, and the Hand Cannon says it needs two hands. Is there a consensus amongst the community about this, or have I stumbled upon something entirely new?

Hand Cannon don't request two hands, but "unless used with two hands or a Recoil Glove, impose a –10 penalty on Ballistic Skill tests". So you can upgrade HC with forearm mounting and shoot with hands free, but at -10 to BS. At least it's how I understand rules.