I am getting one of the X models with 360 lumens and I am thinking about getting one of the VLTOR  SMQ-OEmounts, there don't seem to be a lot of mounts that will fit the .860 body diameter. Alternatively I was thinking about using my old E-Series with an LED conversion if the Quark doesn't work out. I want something fairly slim with decent throw.

Opinions?

http://www.4sevens.com/product_info.php?cPath=297_306&products_id=2686

http://www.vltorstore.com/products/Offset-Scout-Mount.html

Can it be used? Yes. Nutnfancy uses one on his shotgun, I believe.

Should it be used? I think not. The Quark series, while very tough, is not explicitly designed to handle recoil. I would worry about cracking the circuit board as the light is slammed backwards. The Maelstrom series, on the other hand, is designed to handle recoil. You could probably stick one on a .50 cal and it would be OK, as the body of the flashlight actually anchors the battery in place. It's a pretty cool design that I don't think anyone else uses.

I used to have a quark 123 squared tactical in an elzetta mount on my rifle.  I had absolutely no issues with it and ran it for about a year.  That being said, I just didn't feel it was as will constructed as a weapon light should be and I also didn't like the multi modes on my rifle so I replaced it with an elzetta light and I haven't looked back.  The quark was fairly bright and I still carry it from time to time in my pocket.  I like the versatility of the light, but I don't think a multi mode light is suited to weapon use.  I also don't think it is made in the USA, for whatever that's worth.

The tactical model shouldn't have the issues with the modes.

True, I suppose I should clarify.  The tactical model allows you to select and preset two of eight modes.  Once preset, you access each of the two modes by either fully tightening the bezel or loosening it by approx. 1/8 turn.  I basically set one of the modes on full blast and just left it at that.  As long as the bezel never got messed with, which it never did, then it was ok. The reason I didn't like it was because I thought the added complexity of the additional electronics might make it slightly more prone to failure.  Also, the battery on the front end directly contacts the circuit board, as opposed to having a spring in contact, which is apparently important when dealing with recoil.  Since it was on a duty rifle, I just really wanted something ultra reliable.  Again, I never had any problems with it and I still carry it as a utility light.  It's great for that and the different modes are very useful in that role.  For a weapon light, I just liked the construction of the elzetta better.  I did notice one quirk with the quark.  If you were on one of the dimmer modes, when you activated it, it would flash on the brighter mode for a few milliseconds, then go to the desired brightness.  But it only did this the first time you turned it on after not being used for a few minutes.

The electronics in various lights usually aren't much different. The failure will come from the fact that the light is not recoil-proofed. Obviously it worked OK for you, but that's not a guarantee.

Also, the flash you get when you turn on a Quark is called "pre-flash". It varies in intensity from light to light, some have it kind of bad and on some it's not noticeable.