
NEMO
Disco 15 Series
Spacious spoon shape, but bulky and inconsistent warmth.

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You might be looking for a Wiggy's brand mummy bag. He uses hydrophobic synthetic insulation and over stuffs so they last forever. Also the big YKK zipper. It's like a sledgehammer. Heavy dumb and just works.
I have a military sleep system that I've replaced the cold weather bag with a Wiggy's zero degree bag, I've slept down to 20 degree's with no issue and I'm sure it would go lower than that.
Wiggys has some excellent 0F or 20F rated sleeping bags for $112-125 on special (discounted price + stuff sack + pillow + free ground shipping to Lower 48). Made in Grand Junction Colorado from US materials. They loft and insulate like down but don't absorb moisture and can be stored compressed indefinitely without losing loft / insulation. The other nice thing is they come in different sizes, so you can order a bag that fits you better (less volume = faster to warm up). Quality as also top notch, they make sleeping bags and winter survival clothing for the Air Force and Air Guard crews up here in Alaska.
Wiggy bags out of grand junction Colorado I slept cold with every fancy ‘outdoor’ brand bag until I was 20. My dad had been using wiggy bags for a decade at that point and I finally switched after having to cut a fishing trip short due to lack of sleep from the cold. Bought a wiggy bag when I got home. Have been sleeping warm for the last 29 years. All of my friends that have made the switch say thank you for the recommendation.
Wiggy sleeping bag. High r value pad like a thick exped. Ignik heated pad cover if you have power. Sleep in clothes so you don’t get cold taking them off then cold again putting them back on in the AM. Get super organized so you’re not wasting time dicking about. Things that you don’t mind doing in summer warmth can get really annoying really quickly in the cold.
Wiggys sleeping bags are amazing, though not the smallest ever. I would want one in a war zone.
i would look at wiggies over bags, i think that covers 40 degrees. they are a good heavy duty bag, kids are rough. wiggies uses real temp numbers, not just survive the night ratings. if your a larger scout master, they can make you a custom bag 2x wide and 2 x tall. i have ran my 20 degree bag down to about 18 , in a tent . but is way to hot for summmer. but perfect for fall. ive been thinking of ordering a over bag for summer and maybe bring a woobie blanket.

NEMO
Disco 15 Series
Spacious spoon shape, but bulky and inconsistent warmth.
Hammock Gear
Classic Burrow 20°F
Budget-friendly quilt; very warm, but not ultralight.

NEMO
Disco 30
Roomy spoon shape, but bulky and prone to zipper snags.

Katabatic Gear
Alsek 22°F Quilt
Premium quality, very warm, but high price for weight.

Neve Gear
Waratah
Great warmth-to-weight and value, but untreated down.

Ranked #1
NEMO - Disco 15 Series

Ranked #1
Kelty - Tru.Comfort Doublewide 20
Ranked #1
Enlightened Equipment - Revelation APEX

Ranked #1
NEMO - Disco 15 Series
Ranked #1
Hammock Gear - Classic Burrow 20°F

Ranked #1
NEMO - Disco 15 Series