Hello. My on-duty/off-duty issued shotgun is a Mossberg 500 Cruiser 5-shot bead sight cylinder bore. Nice shotgun. I have it's slightly bigger brother the 590 9-shot with ghost rings at home. I've wanted a light on it for some time but several things were presenting problems. Lights that were too long or wide. Lights that had tri-mode settings like HI/LO/Strobe. Rear tailcap clickie switches that wouldn't work because of the magazine cap being too far forward against a short muzzle, meaning not much room to "negotiate" your thumb into the gap without the light being far out in front of the muzzle. Pressure switch tailcaps pushing the lens out in front of the barrel crown. You get the idea........ I got it figured out and it's working wonderfully. A 220-lumen CR123 CREE LED that has a twist switch for ON/OFF, uses primary batteries or RCR123 rechargeables, seems rugged and so far is not proving me wrong in test firings with slugs. The light has tremendous throw (220 lumens) for a 1-cell CR123 and also provides about a 40-degree flood in addition to a really hot center. Downside: a 40-min life to reach 50% but what the hell. Batteries are cheap and I don't have to remove the light to change the cell, as the front unscrews off. I clamped it to the gun with a Tac-Star (Lyman) clamp mount that aligns the hot spot of the beam right center-punch with the front bead sight. It's effin perfect alignment, I tell ya. Didn't have to "adjust" a single thing. So I have to turn it on/off with a slight twist. Big deal. It works for me. Here's what it looks like. Thanks for looking.