Military sleep system

[daddyusmaximus]

Love my MSS. I don't worry about the weight as much because I'm not gonna be hiking a long ways anymore. I mostly truck camp. The flexibility of the 3 pieces to mix and match is great for the money. (Free, I just kept mine when I retired) I also have a poncho liner that I had an old sleeping bag zipper put in. I use that or the MSS green if I need to go light.

[HansTheHobbit]

I have pretty extensive experience with backpacking gear. Long story short, yes you can get better equipment, but it's going to cost you.

The bivvy sack from the military system is pretty good quality. You can get lighter bivvies, but they're going to be less durable. GoreTex makes three levels of fabric, and I believe the military system uses the heaviest, which is pretty bulky. GoreTex bivvies are pricy, but it's worth it, as others will be far less breathable, and moisture control is extremely important in cold weather. So for the price the military issue bivvy is a great value.

The actual sleeping bags aren't that great. First of all, having two sleeping bags that fit inside each other is a terrible idea. It adds lots of weight, and the larger bag isn't going to fit right, which will hurt its temp rating. I can't speak to the quality of the synthetic fiber, but I think that their temp rating is extremely optimistic. I've spent time in synthetic bags that were roughly the size of a VW, and I wouldn't take them below about 20 degrees. To go very far below freezing and still have a bag that's reasonably lightweight, you need down.

On the other side of things, temps above freezing require synthetic, as moisture is a no go with down. In high humidity, down bags are next to useless. In other words, you need synthetic for most of the year and down for the dead of winter. Which is hard if you live in places without distinct seasons, where you can go from 20 degrees to 70 degrees in a week. I've spent Christmas in shorts, only to be iced in on new years. For places like that, a good 20 degree synthetic bag is regarded as standard equipment for winter. It will likely cover you most of the time, it's reasonably lightweight, and you won't freeze to death if the temp goes above freezing and the humidity gets out of control. This would be for places like Oklahoma, Kansas, Northern Texas, Arkansas, etc. Northern states will require a dedicated down bag, plus a 20 degree synthetic for fall and spring. Once you go below 20 degrees, the synthetic bags can no longer be transported; they're too bulky and heavy at that point. The one exception to this rule is the high desert. If you live in a place like NM or AZ, then down is good to go all year. Which is nice, because a summer down bag, say rated to 50 degrees, can fit in a cargo pocket. Down is amazingly light, compressible, and durable; it just won't insulate when it gets wet.

So, the military bag is okay for some climates, not great but not terrible, but there are better options. The other thing about the military system is that synthetic fibers aren't very durable. They degrade rather quickly, and synthetic bags lose their temp rating much quicker than down. So those surplus bags might not have much life left in them, even if they look to be in good shape. A sleeping bag can only be compressed so many times before it's just not worth using anymore.

Another thing you will want to consider is that bivvies are only appropriate when there's no chance of rain, i.e. the temps are comfortably below freezing. If you try to use a bivvy in heavy rain, everything will get wet.

[HansTheHobbit]

I forgot to add this, sorry. One of the most important things with a sleeping bag is moisture control, if not THE most important. Humidity determines the real world rating, and excess moisture buildup will turn a 0 degree bag into an icehouse. Even if you don't feel sweaty, you're always perspiring, even in the cold. That moisture has to go somewhere, so it's vital that the bag provide a good escape route. That's the fundamental flaw I see with the MSS is that you're dealing with four layers of nylon fabric instead of two. I think those things would hold moisture like none other.

Regarding wearing clothing to add rating to the bag, that can actually work against you, which is where the myth came from that going in your bag butt naked will keep you warmer. While being naked isn't necessary, unless your underwear is cotton (which it shouldn't be!), you do need to get rid of superfluous clothing that doesn't insulate and can hold moisture, such as a pair of pants, especially if it's a shell, be it soft or hard. Now, insulated clothing can help, but you have to make sure it's worth it. For example, a heavy down coat will definitely add more rating than it takes away. But a softshell jacket with a light fleece lining will remove more rating than it adds. Of course the humidity will determine what you can and can't get away with. In very dry conditions, that softshell may actually help you slightly.

To get the most out of the bag, wear a next to skin baselayer (with socks, glove liners, and cap) into the bag, nothing else. That will start wicking moisture from your skin as soon as it leaves the pores, which will dissipate it quicker. Then use a silk or wool bag liner. They're expensive, but well worth it. The point is not to lower the temp rating, although some claim to (they don't deliver on those claims), but to help with moisture control, as well as to keep your oils from screwing with the insulation. This wicking system will keep moisture moving, that way the bag fabric doesn't get saturated with sweat and become a barrier.