i am planning a backcountry hunting trip in mid october for high elevation(11500+) into colorado. i have a concern about sleeping bags... and a possible solution to my main concern.

the deal is it could be 50*F at night or 0*F...i have a north face cats meow +20 bag that i have slept in to 17* but i was cold....i also have a double big agnus 15*F bag...i was thinking of taking both bags and if its cold simply slip the north face inside of the big agnus....(there are 2 of us going both with cats meows).

has anyone tried this? buying 2 new sub0* bags really is not an option unless absolutely needed.
what do you all think about this idea? i guess i could climb into the walk in freezer at work and try it! LOL

I'd say that if it's not too tight of a fit it should work pretty good. I use a lightweight Coleman fleece bag inside my sleeping bag when it's cold. That works great.

Having a decent pad under your bag will help too. So does wearing a nice fresh, dry, layer of clothing. Long underwear does help keep you warm in a sleeping bag.

I also carry a piece of that bubble wrap type insulation they sell at building supply centers. The kind that has the shiny foil-like stuff (mylar) on one side. I put the shiny side up, under my bag. I think it helps keep me warm, but that's really just an opinion. I've never really measured the temps inside the bag to try and prove it.

To be sure you really have to test it out though. Just don't let the boss catch you sleeping in the freezer

Bill's point about having enough insulation under the bag is well taken. You don't want the cold from the ground sucking warmth out of you, obviously.

As for the two-bag solution, as he says, it sounds like it should work. The main point is to increase the dead air space around your body. There is probably some semi-official recommendation about how many inches of loft are required for which temps, if you were to poke around the internet.

What you are talking about is using one bag as an "overbag." I have a very lightweight bag made by MEC just for that purpose. Overbags work if, as already mentioned, there is enough room for the inner bag to loft up, otherwise, you lose the effectiveness of the inner bag. Overbags are not the ideal solution because of the extra weight. Another solution is to rent a winter bag, rather than buy one. I've got an old Cat's Meow. Mine is only good as a summer bag because the insulation is pretty well flattened.

I used a double bag setup for six months in Antarctica in temperatures to -45°F. Other than weighing about nine pounds, it worked out well. I stayed warm and slept well. It did take a while to bring the assembly up to operating temperature when I first slid in but shivering works wonders. I had a 2.5" foam pad under me and seldom felt cold from below.

i do use a sleeping pad..1.5 inches from head to toe. the cats meows both fitt well inside the big agnus...its a monster bag. you guys have elieved my stress about it...i guessed it would work but have never tried sooo......