Ok well I mounted a cheap light to the rail on my 92F and put a box of rounds through it. It held up just fine. The light mount is flimsy and cheap so if it failed I have no idea what I would've blamed for it.. the light or the rail... but it didn't fail so I'm out ok I suppose. I wanted a cheap piece on it because I figured if a cheap one didn't fail then your good stuff isn't likely to fail either.
Like I say it doesn't lock up tight... but its a flashlight so it doesn't have to.
I can't say it changed the way the weapon ran. I blasted away with reckless abandon trying to make it let go and it never did.
So there ya go... if you are looking to add a rail to a pistol of yours... this is a real option.
And you can get them off amazon.