BTW, grenades are useful for breaking down doors.
inanimate objects have a damage threshold, below which you can't even do armor damage. Since grenades are always area attacks (even anti-armor grenades are SCATTER) they always end up doing 20 attacks for 1 damage (or whatever their DC is). Similarly, I could shoot a plasma cannon (DC15 BV9 LINE) at a door all day and never damage it. My dual laser rifle cuts through typical doors it in a few shots. A BRUTAL attack will always do some armor damage, even to a door, so a gyro mace would be guaranteed to eventually get you in. If I don't have a good door-breaking weapon or any code-breaking skill or lancemates, I carry the laser drill (DC 19 emelee) from the hogye mines. It's nice and light.
BTW, code breaking gives ridiculous amounts of XP. I waited until I had a good lance together and then did all the doors in the ziggurat, and that gave everyone several thousand XP.