I guess if the door's breakable with a kick, that it'll be breakable with an AP rocket, too. Actually, it'll just disintegrate on impact.
The shotgun with flechette rounds might work pretty well on the lock and hinges, too.
I suggest to sort out common mechanics not only for how the door can be broken, but also repaired and reinforced/barricaded.
We have Engineering skill which can be pretty much applied to the whole door thing.
For example:
- Basic wooden door, which can be found in 80% of all the houses in Phoenix. Imagine it has 250/250 Hitpoints and die-cast resistances which cannot be altered. Let's say it's 40-50% DR to Normal and 0% to Explosive. It can be targeted by the following weapon categories:
- Selected melee weapons (fists, powerfists and gloves, sledgehammers -- not spears, knives or baseball bats)
- shotguns, if possible -- only bullet/flechette rounds
- splash-damage weapons: grenades, GLs, RL
- actually, a flamethrower could work too, it's just harder to imagine.
It'll take a person up to 5-6 shotgun blasts, or a couple of 40mm grenades, or a single rocket to bring it down.
Depending on the Engineering skill, one can reinforce the door, adding hitpoints to its base value. For example, with 100 Eng skill the door can be reinforced to have 50 + 100/2 = 100 additional HP, which sums in 350. Same mechanics can work for repairing of destroyed doors.
It can be also a good idea to have an expendable resource needed to reinforce the doors, like wood, metal parts and junk.
Please take notice that all written above is just a single example of a concept, which isn't to be taken as a ready-to-go idea.