Before I go any further, let me wish you good luck and God speed on your upcoming deployment. Thank you for your service!
I recently purchased my first AR15 platform (a Bushmaster) and I am learning quickly that it requires a different amount of lubrication (read more) than I have used with my other rifles. I would love to have you write a column about your recommendations as to maintenance procedures and lubrication of AR15 type rifles with particular recommendations of particular type of lubricants. I am also interested in what you might do to prepare the rifle for cold weather use. Your profession makes you an expert. Thanks for everything.
TOR here: Thanks for the kind words. I would like to congratulate you on getting a nice defensive rifle. Hope you have fun with it at the range and are comforted by its presence in your home. Onto the maintenance question.
I have been carrying and shooting the AR platform for a long time, both for work and fun. I have used them in the desert, frozen central European winters and the primordial deep South as well as a few other more mild climates. I've shot most models and many makes. However even with (damn I feel old) this bredth of experience as always YMMV.
Personally I think that the necessary amount of maintenance to keep an AR running has been greatly overblown by a small very vocal minority. Remember that girl from your home town who everybody was sure was totally slutty but it was all 'I know a guy who knows a girl who said this and that' kind of stuff? Nobody had personally been involved with anything but they just sorta pass stuff on. I think it is a lot like that.
First lets talk about the need for maintenance. I would say that a field cleaning (we'll come back to this later) every several hundred rounds of shooting, or bad weather/ high humidity day in the field is a good idea. However that is pretty much standard advice and a good idea for all firearms. I would say that once in awhile, every few cleanings, maybe after an intensive shooting course or before you put it away for the winter doing a full cleaning is a sound idea. If you have some issues or plan on caching an AR then going crazy on the cleaning makes sense.
I am sure with the second sentence of the last paragraph five people went 'aha' that it is clear evidence you must clean an AR every day for it to work. I did suggest field cleaning daily if you shoot a lot or are in bad gun weather and will stand by that. An AR will work for a long time in these conditions without cleaning if you keep it lubed but just like your kitchen, if you let it get to be a complete mess cleaning up sucks. \
It is also worth noting that comparing the AR's need for maintenance with an AK is kind of apples and oranges. To say that the AR is unservicable because needs lots of maintenance as measured by it requiring more than the AK is about as valid as saying that the AK is not servicable because it is unaccurate as it is less accurate than the AR. The decision (if you can afford it don't choose just get both) has a lot of complicated factors but both are good guns. Anyway.
A field cleaning goes as follows. You will need a rag, bore brush or snake, and oil. Nothing else, all that stuff is for the full cleaning. If you are in the field after finding a nice place (soft, shady in the sun, dry and warm in the winter) and take off your hat. Set your hat on the ground in front of you. Shotgun your AR (remove the back pin, and open it sorta like a break action shotgun. Next pull the charging handle and remove the bolt carrier group and charging handle then set them in your hat. Take your rag and wipe out the inside of the upper receiver. Get that clean and then go to the chamber. Remember your goal isn't to get it absolutely perfect and spotless but to knock off the big chunks of carbon, sand and grit and such. If it takes more than 5 minutes you are dilly dallying. Clean the bore real quick. Next pay a bit of attention to the bolt carrier group by wiping it off. This should take maybe 2 minutes. Give the charging handle two swipes (top and bottom) and everything is clean. Lube it up and put it together. The whole thing shouldn't take more than 10 minutes.
Lubrication as you mentioned is a bit different than other rifles. AR's like to be kind of wet. A light coat on all the internal parts is a sound idea. If oil is dripping off the weapon or drops of it are running here or there it is too wet. As for types of lubricants I am not very picky. I have used gallons of CLP, cans of Rem oil, that random oil that comes in generic cleaning kits and a decent amount of militech. Militech is by far the best. It is kind of expensive and (at least I've heard) you need to totally remove all other oil before using it but that stuff is awesome. The rest I would consider functionally equivalent.
My observation is that AR's will run for an indefinite period of time if you keep them lubed and do regular field cleanings. This is a great example of the 90/10 rule. You get 90% of the payoff of cleaning for 10% of the effort.
When it comes to the AR platform I don't think the importance of lubrication can be overstated. Really when it comes to the field cleaning it is less about removing junk and more about getting oil on the moving parts of the gun. A word of caution on the color of oil on AR's. Since the direct gas impingement is a dirty system some carbon gets in there. The tiniest bit of carbon will turn the oil slightly dark or black. When it stops looking (texture and thickness not color) and moving like oil or there are chunks of carbon is more important then that it gets a bit grey/ darn after firing a couple mags. Also in humid or wet climates you need to get that moisture off the outside of the weapon regularly. While I haven't personally tested it to the extreme I would wager an AR will shoot for A LONG TIME if you just keep oiling it.
As for the 'I won't have time to clean a gun every day if (enter your worst case scenario)'. In fact to be honest most days you will be so bored you will give it a quick once over if it's needed or not. I would say that baring a true Alamo/ Rourke's Drift type scenario you can definitely take a few minutes to maintain an AR.
A full cleaning is a good thing to do every now and then. I tend to do it after every trip to the range but that has a lot to do with force of habit and not much to do with actual necessity. For that I go home, lay out a towel and disassemble the weapon (take apart the bolt carried group and bolt) onto said towel. Clean all the individual parts and then attack the inside of the upper receiver and chamber. Use gun scrubber or carborator cleaner or Hoppes if it suits you. Cue tips help a lot here. You tend to go through a decent amount of them but they are cheap and a lot come in a box. Typically one of those big boxes gets lost or relegated to generic household duty before it is used up cleaning. Also a couple of pipe cleaners for the gas tube are a good idea. The chamber is the annoying part. That it isn't easily accessible and has that weird star pattern makes it hard to clean and get to. After the big chamber brush you go to the cue tips. It takes a lot but they are cheap. After that a piece of paper towel on your pinkey finger twisted around in there gets it done. I tend to do this sort of cleaning when I have time and am not in a hurry. It typically takes about two beers to get it nice and clean.
I hope that helps answer some of your questions. If you have any more then just leave them in the comments section.