I wanted to mount a laser sight on my sort of new 4003, but ran in to the problem that likely many encounter with this non spec rail -- nothing fit
I finally found a laser-only that works; an ARMALASER STINGRAY SR1.
It's similar to another companies laser except it fits the TSWs.






Very happy with this light, it locks on tight and holds its setting, not to mention it's about half the price of a Crimson Trace laser grip and its sleek design should fit in most holsters. Gets 5 stars from me.