Mine's also machined from a block of "aircraft grade" aluminium. My friends kid me about my monthly cleaning regimen. "It's not a gun, stupid!" I strip everything down, clean the threads, O-rings, reflectors, bulbs, and lens with alcohol, then lubricate the threads, O-rings, and electrical contacts with synthetic silicone grease (I repurposed a tube of brake grease from the garage). It does a lot to keep dust from getting past the O-rings and contaminating the threads or wearing down the rubber, but you should find out if you have silicone O-rings. If you do, I think you are supposed to use a petroleum-based lubricant. It's the opposite for non-silicone O-rings - petroleum will break those down, and silicone grease will break down silicone rings. :doh:
It's been a while since I've paid attention to the WalMart displays, but don't the Duracells sell for something like $16 for a two-pack? You can get the batteries much cheaper than that. The cheapest "quality" batteries would be from 4sevens.ca, that's about 1.92 CAD each, including shipping and tax, for a pack of 50 - that might be too big of an order if each set lasts you a few months. BatteryStation.com ships from the States (I think), but their cells are made by Panasonic in the US and they price them at $1.50 USD each before shipping. If you email them, they tend to give discounts for LEO/military types, and firefighters are probably included. With the discount, they might be even cheaper than 4sevens unless they ship by UPS or FedEx (watch out for those cross-border brokerage fees). 4sevens is the only Chinese-made cell that I would trust and are comparable to the USA-made cells like Panasonic, Duracell, SureFire, and BatteryStation, which are all manufactured by Panasonic (they have the only plant in North America making 123A cells). Even though they are the only plant, each cell is made to a specific company's specifications (i.e., a Duracell 123A could be made 20 feet from a Panasonic 123A, but they are each made to separate specs.). Even though you aren't using rechargeables, you should keep a multimeter next to where you store your batteries or your duty stuff, and check the cells for equal voltage before you put them in. If you happen to get a DOA cell and put it in series with a fresh one, bad things will happen. I should dig up the news article where a LEO had his Pelican ProPoly light explode in his hands from mismatched 123A cells - don't want that to happen next to your face. Also, if some of the safer rechargeable chemistries like lithium manganese are safe enough for firefighter use, keep in mind that rechargeable cells are rated at 3.7 volts and top off at 4.2 volts - quite a bit more than 3.0 V lithium primaries. The common configuration is a single 18650 rechargeable cell to replace a 2x123A configuration (6.0 V > 4.2 V) or what I have, 2x18500 to replace a 3x123A configuration (9.0 V > 8.4 V).
I actually find it surprising that your LEDs cut through smoke better. Are they a particularly warm colour? That makes me feel better about investing the $60 or so for a LED upgrade when my incandescent lamps burn out. I'm shooting for 800 lumens at the emitter.

Might be too much light for smoke and fog, but I can modify whatever the detachment issues me once I get on into a 80- to 120- lumen spot beam for those foggy or smoky situations.
My name is Squishy and I have a flashlight problem. :bill: