There are litterally thousands of targeting lasers out there for all types of firearms, ranging from sub Watt red dots to big mean blues and greens. Physical shock is not as much a durability issue as you might think in as much as the shock is in one direction. The big problem seems to be with putting them on air-rifles and pistols. For some reason, unknown to me, they have a bi-directional recoil shock that plays havoc with optics and laser diode internals... go figure.
All that aside, let me throw this out for your consideration: If you are in a situation where you want/need rapid target acquisition (usually low light conditions), Do you really think it is such a cool idea to be waving around a beacon that says "Hey, I'm over here! Shoot over here!"?
B.T.W. I've got a couple of pistol laser sights. Little, low power, red dot types. Sitting in a drawer, somewhere. And a '200 mW' (ha ha ha, more like 30-50 mW) long gun greenie that I use for a star pointer. Seemed like a neat idea at the time, cool toy and all that, but just don't see much use for them on firearms now. IR spotter and NightVision system, now that is a different issue all together, BUT,, If the other guy has NVS too, yer screwed...