According to the RAW firing into melee gives a -20 penalty and that’s it.
I have two problems with this. a) There is no chance to accidentally hit an ally, which is the real danger when firing into melee. b) Firing full-auto into melee is no more dangerous then firing a single shot.
I’ve thought of three possible solutions to problem a)
1) When firing into melee, if the shot misses by less then 20, an ally is hit.
This the rule my group typically uses. I don’t like it as this exact rule exists for a creature when it has attached itself to a player (its in Creatures Anathema I think). Having the same penalty for just being in melee seems a bit harsh, and it makes the creature far less dangerous.
2) When firing into melee if the shooter rolls X or higher an ally is hit.
I don’t like this as it this sort of thing is already handled by the weapon jamming rules. Moreover, it would make good/best quality weapons more likely to hit an ally and I don’t want to make better quality weapons worse than lower quality ones. Lastly, if the range is two small this will rarely come up, if it’s to large then it might overlap with actual hits and I want to avoid that.
The advantage of this rule as is does combine well with my solution to (b)
3) When firing into melee, if the shooter gets two or more degrees of failure (ie misses by more than 20), an ally is hit.
This is the rule I’m thinking of using in my group. I like it for several reasons. First, it punishes characters with worse BS more. I’m okay with the idea of a gunslinger/sniper so skilled he can casually shoot into the thick of combat. On the other hand less skilled shooters should either be cautious (aim, get into point blank range) or switch to melee weapons.
Second it uses a concept already contained in the rules, degrees of failure. Lastly it combines really nicely with my solution to (b).
My solution to (b), that is making it dangerous to fire automatic into melee, is this.
When firing full or semi automatic into fire each successive round that does not hit is considered as having been rolled at 10 higher than then the original roll for determining whether an ally is hit.
Here is an example using this with option 3:
Adam is being hacked at by an ork nob. Adam’s ally Ben fires his bolter full-auto at the nob hoping to kill it this turn. Ben if 50 meters away from the melee, so he is rolling against his BS of 45 (-20 for firing into melee, +20 for full auto) and will hit Adam on anything over 65.
Ben rolls a 43, success with no degree. The first boltshell hits the nob, but the remaining three miss. The second round is treated as a roll of 53, the third 63, and the last 73. This is over the threshold of 65 so the last round hits Adam.
I think this does a good job of discouraging reckless automatic fire into melee. I’m considering making semi-auto only add +5 per miss to make up for the difference in bonuses and give semi-auto a boost. I’m also considering a cap to the number of hits the ally takes so that heavy bolters etc aren’t more dangerous to allies than enemies. Either half the number of rounds fired, 1d5 hits, or a flat 3 hits.
I’d be interested in hearing your opinions on this.