Chief Brody posted test of his Remington 870 with Streamlight TLR-1 on Remington 870 Forum:

Meant to do this a long time ago, and wish I could do a better job – but anyway this’ll give you a good idea of how this particular light works. My camera wasn’t really getting the job done with the apartment any darker than it is, but you can see – the Streamlight is plenty bright with the lights ON. I’m a righty, and I have the TLR-1 mounted on the right side of gun, with Streamlight’s magazine tube mount. I can easily manipulate the switch using my left index finger, without shifting the rest of my hand on the forend. I took these holding the shotgun with my right hand and the camera with my left – that’s a workout!

This first shot was taken with the camera aimed at a mirror, I promise I didn’t lie about which side the light is on.

Remington 870 with Streamlight TLR-1, Indoors

Remington 870 with Streamlight TLR-1, Indoors

This is about 20.5′.

Remington 870 with Streamlight TLR-2

Remington 870 with Streamlight TLR-2

Here is 13′, keeping in mind typical home defense shooting distances.

Remington 870 with Streamlight TLR-2

Remington 870 with Streamlight TLR-2

Remington 870 with Streamlight TLR-1, Indoors

Remington 870 with Streamlight TLR-1, Indoors

Remington 870 with Streamlight TLR-1, Indoors

Remington 870 with Streamlight TLR-1, Indoors