No, sorry, it won’t fit.

Sorry will not clamps over ur trigger guard and sites on ur front rail .where u don't have one it may fit on but will not hold .being sighted in at all .look up type of gun u may need one goes on ur spring in rail remove ur pin replacement is the lazer.which they work pretty good all inside ur gun

Sorry but this will not work. James & I posted links that would work in your 2nd question.

Good evening to you!! No sir the Crimson Trace Laserguard for S&W M&P will not fit your S&W 5903. Sorry. Have a good rest of your night.

Hi Rich and welcome. Unfortunately, no Sir. Cheers and stay safe!