Anyone making a decent weapon light that uses AA's?

I believe some (lucky?) British Army use a light/laser combo that is powered by four AA's.
German made if I recall correctly...

I've never seen one myself. Could be making it up as they may have seen the error of their ways an released an SF123A powered version.

Al

I don't think it's an issue of AA vs. 123, but an issue of Lithium vs. Alkaline.  For the load being put on them, the lithiums are far better than Alkalines for running incandescent lights-- they keep their voltage higher under load and over time.  SF 123's are (now) cheaper than AA Lithiums.

So I don't think there is much demand for a AA weaponlight, since seems easier to procure 123s than redesign a light.

AA sucks.

From Surefire:

[b]Battery Basics[/b]

The choice of the type, size, number and quality of the batteries- or cells in the case of a battery stick- largely determines how powerful the light can be. It is the battery that determines how much the light output changes with time, during use, and how long the flashlight runs. The battery also determines how the flashlight performs at low temperatures. The choice of batteries also largely determines the size and weight of the flashlight and its operating cost. And, finally, the battery's self-discharge rate has a significant effect on its practical operational reliability. Let's begin our discussion of batteries for use in flashlights by dividing the candidate batteries in two categories: primary and rechargeable. While the first question to address is probably which category to use, that question can't be adequately addressed without first looking at the best batteries that are available in the two categories. So let's look at the readily available primary batteries that are the most obvious candidates for flashlight use. The most common of the alkaline batteries are the AA, C and D sizes. In the lithium manganese dioxide battery, the most common size is the 2/3 A size. Alkaline batteries in these sizes are widely used in all sorts of consumer products, from toys to flashlights, and their cost is modest compared to almost all other types of batteries.  


The 2/3 A size lithium battery, by comparison, was developed for use in cameras and other professional applications and costs considerably more. [b]The big difference between a lithium battery and an alkaline battery is that the lithium can deliver over four times more power (watts) without overly excessive voltage decline over the batteries discharge period. An alkaline battery simply cannot deliver high wattage without its voltage declining so sharply that it makes the battery unsuitable for flashlight applications, unless some sort of electronic voltage control is utilized. The lithium battery also stores almost 50 percent more useable energy than an AA alkaline battery, is about 30 percent shorter, is lighter, and has a 10 year shelf-life as opposed to about three to four years for the AA alkaline battery. [/b]And, finally, the lithium battery has far superior low temperature performance, and will operate at temperatures well below those where alkaline batteries fail. On the practical side, historically the lithium battery has been more expensive and harder to find than AA alkaline batteries. However, that situation has changed.
It used to be that the only manufacturer of the 2/3 A size lithium battery was Duracell, and they could really only be found in camera stores or purchased from those retailers selling SureFire lights. But that was more than a decade ago, and now these batteries are made both in the U.S., Europe and Asia- not just by Duracell, but by big names like Panasonic and Sanyo, plus a number of other lesser companies in Korea and China. It is fair to say that worldwide availability of the lithium battery in normal retail outlets is no longer an issue, and if you shop intelligently, their costs have become quite a bit more reasonable- just don't by them in camera stores. That said, a word of caution is in order on lithium battery quality (or performance) as it relates to which brand to buy. Just like with alkaline or other batteries, the lesser brands- and even some premium brands with lower costs- don't perform as well. Where this really shows up in lithium batteries is when they are used in voltage-sensitive, high-drain-rate applications, like in high-power flashlights or WeaponLights. While performing similarly in the beginning when they are fresh, these lesser lithium batteries exhibit greater voltage declines later in the discharge cycle, resulting in substantially less light output in the last half of the flashlight's operational run time. Fortunately, there is a way to be sure of getting the best performing lithium batteries available, and at the same time getting a price substantially less than normal market prices- use the SureFire SF123A lithium battery, available directly from SureFire on the www.surefire.com website, or from any retailer of SureFire flashlights. The SureFire SF123A is the standard 2/3 A size lithium manganese dioxide batteries that are "private labeled" for SureFire by one of the major brandname battery manufacturers. They are made in the U.S. and according to our extensive testing of all of the available lithium batteries, they perform the best for our type of application. You can buy SureFire batteries in complete confidence and know you are getting the best available 2/3 A size lithium batteries, and getting them at the most competitive price. It should be clear by now that 2/3 A size lithium batteries- in particular the SureFire SF123A lithium battery- is the overwhelming performance choice for a primary battery in a flashlight application. This is clearly apparent when you compare the size, weight and performance of the lithium-powered SureFire flashlights and WeaponLights with the best alkaline-powered flashlights on the market. The SureFire lights are so much better performing that they are in a class by themselves. While this is not entirely due to the use of these lithium batteries, the lithium batteries were necessary to achieve these results.