Surefire 618FA unit with KL5 head installed!

**Cesiumsponge** · 03-12-07, 20:37

I got the Surefire 618FA and KL5 head today for my own Rem 870 project

Thanks Grant!

It is 100% compatible, no problems or issues at all.

The KL5 head is brighter than the OEM head, and the beam is much more diffuse and widespread. The overall whiteness of it also makes it appear much more brilliant. The OEM xenon head is very focused and yellower (typical) beam when compared side-to-side. This image doesn't do a perfect comparison due to my lack of exposure metering controls; the (cheap) camera autobalanced but the LED is actually brighter if both were exposed for the same duration.

I think the more diffuse, wider beam of light is of great benefit for home defense since I personally think you would want maximal area coverage inside a building, not a tight, focused beam that'll give you peripheral vision in the dark. That is more suited for outdoors use where you need long light throw. It is also a solidly made LED unit. I tried opening it up to take a look at internal construction methods but couldn't unscrew any part(s) of it and didn't want to try any harder in case it was purposely sealed to prevent tampering. I don't expect it to break. Same dual spring construction as traditional Surefire shock isolated bezels, plus LEDs are solid state and have no filament to bust.

The OEM head size is 1.715" in length and 1.375" diameter. The KL5 unit is 2.185" length and 1.470" dia, which makes it slightly larger, but that shouldn't pose any clearance issues. The KL5 is about double the weight of the OEM head, but this component isn't heavy to begin with in the overall scheme of things. In fact, the addition of the KL5 adds about the same weight as one 00 buck shotshell.

I highly recommend this for anyone that already runs the 618FA unit and wants to add more without buying an entirely new system. It won't quite put you in 918FA territory as far as light output but you can get something in between without adding much weight or size (the 918 looks way long!), and you don't have to worry about the dreaded xenon power dump when the batteries run low and output practically dissapears in 30 seconds.

As mentioned on Surefire's website, the benefit is a brighter beam-- 100 lumens of output for one hour followed by 3 hours of useful light output, and plug-and-play. From what I have seen, it should also be much tougher, provides a better beam profile for home defense in my opinion, looks more brilliant due to the spectrum output, and looks wicked

**Logan Moody** · 03-13-07, 13:15

Very nice setup, you'll need to let us know how it holds up after serious use!

BTW, I can's help but wonder what kind of sight setup you have on there. I have been looking for some high profile sights for my issue 870 so I can use them in conjunction with optics.

Logan

**Cesiumsponge** · 03-13-07, 20:04

I use a Cavalry Arms SST-870 front sight setup, which uses an AK47 post. I replaced the AK post with a tritium one. It works with the high-tube adaptor w/ rail from Cavalry Arms by default. I assume it works with the Mesa Tactical high-tube mount as well. I have it working with a GG&G MAD tritium BUIS mounted on a KAC 870 RAS right now and I'll be using a Mesa high-tube down the line.

I honestly had terrible, terrible, terrible luck with the unit and wouldn't recommend it unless you want to do some work on it and you're handy with tools. Unfortunately I think it is the only game in town if you want a long sight radius using the aftermarket high-rail type adaptors or rails, otherwise you're limited to throwing a BUIS on the front and rear of a rail on top of the receiver for a wimpy pistol-like sight radius. If there is another, let me know. I was thinking of a barrel mounted rail clamp with an AR-15 type gas tube or rail mounted front BUIS but I don't have enough stuff floating around to see if that would work without purchasing the parts.

The screws are -just- long enough to fit flush when its tightened up, and its incredibly hard to get it all aligned and tightened down. Two screws per opposing side on the sight/clamp itself. Two more up top which clamps an aluminum piece (that houses the front post) between the two wings. I had to file down the bottom of the aluminum piece to get it to fit on the top of my barrel otherwise the screw holes up top wouldn't align. I stripped out one hole at the bottom because of the incredibly difficult fit. There are only 2-3 threads on the steel wings/clamp because its thinnish metal and the screws are flush, so good luck getting a screw started without tearing out the first thread. They shouldn't have provided flush screws like that when you can't even start them without damaging the softer threading on the steel.

I used it on an 870HD, if that makes any difference. The 870 line should all be identical dimension-wise for all practical purpose.

I can always retap the hole and use a larger screw, use nuts, weld a nut on the inside for more threading, etc, but a commercial product shouldn't require end-user work. Right now I feel its poorly designed and not worth $40. It needs more R&D work on it and I feel let down since Cavalry makes a lot of useful gear.