[impromptu Quote]Interesting volley fire rules. Apart from anything else it could speed combat up quite a bit. I'll need to give some thought to questions of balance (and I'm not 100% convinced that this should be usable to make a group able to take down a space marine if individually they wouldn't be able to even scratch him).[/impromptu Quote]
Thing is, taking down tough targets like Space Marines is what those rules are intended for, and the fact that it allows for a group to bring down a target that they individually would be incapable of harming means that they work as intended... Massed firepower for greater effect than the firers would be able to achieve individually. It works round the issue of a weapon being improperly potent if it could take down a given hard target solo, while still allowing groups to stand some chance of doing that if working together (bearing in mind that 7 guardsmen with lasguns - a full squad minus the special weapon operator and the heavy weapon team - is only actually dealing 1d10+7 E, Pen 0 with those rules... it's enough of a chance ot make a difference, but it's hardly world-shattering). It's also primarily intended for NPCs, rather than player characters (who will generally be armed individually and thus not exactly appropriate candidates for rules of this nature).