I suggest you get a KL2 for your M3 rather then a BeamShaper if you want diffuse light from your M3. Unless of course you need to switch between beam and diffuse. I think that using a BeamShaper on high powered SureFires is such a waste of batteries. I have an E1e+KL1 for close up work. It's really easy to carry in addition to a larger SureFire and will help you make the best use off SF123As.
Respectfully,
Al