prefetch: A lot of valuable advice in the above posts. Valuable or not, here’s mine…
First: A link to posts I've previously submitted on this and related topics (i.e., how much stuff / what type of stuff to carry):
http://thehighroad.org/showthread.php?t=430877&page=4
Second: I think you need to further define your scenario and goals before you sink money into refining the expensive contents of multiple BOBs. It's always good to plan for contingencies, but you can rapidly get lost in the "widget for every problem" continuum. In your attempt to generally cover all contingencies, you wind up under planning for the most likely / most dangerous events, over planning for unlikely occurrences, and ensuring that you have killed your survivability by overloading. Stay out of the Widgiverse and make minimized weight your goal. Carry items that can perform double or triple duty. Avoid overloading yourself with “backups” for a given functional area; you don’t actually need to carry 5 different ways to start a fire.
That said, here are some fundamental questions that need answering before you start throwing together gear:
1. You said that you are planning to build four bags. Exactly who will carry them?
Will they all be for you? Perhaps you intend to store at separate locations (work, home, off-site storage, or bug-out location). Perhaps you intend to emplace pre-positioned and hidden caches along your route of travel?
Or, are they for other folks? Family? Friends? Trusted or unvetted? Adult males? Females? Children? Your children…or someone else’s? Physical condition, limitations, and capabilities for all involved? Eight year olds can’t carry 50 pound backpacks.
Whatever your load out, the term "bug out" bag implies that you can carry it easily for many miles and that you can RUN with it for at least several hundred yards. If it's heavier than that, you are humping a ruck; you are hiking at slow walking speed with a heavily loaded backpack.
2. What weather and seasons do you anticipate? (edit to add prefetch's location: High Desert Rockies...Got it...Very familiar with the area)
Do you live with four seasons having extreme temperature or precipitation differences? Or a year-round mild climate? Expected or potential drought, heat waves, humidity, rains, floods, forest fires, snow, ice storms, earthquakes, magma, plagues of locusts, etc…?
Equip yourself to handle the most prevalent/likely environmental threat before you start worrying about outlier problems. Will lack of winter clothing kill you long before you are hungry enough to need a fishing kit? People love to include fishing kits in survival packages...without checking to see if there are even fish-able waters in their area. But they forget to include winter gloves and hats.
3. Across what type of terrain would your movement path most likely take you?
Prairie, woodlands, urban warrens, suburbs, desert, mountains, hill country, moving along paved roads or highways, following or crossing streams, creeks, swamps, rivers, coastal waterways? Do you need to cross any non-fordable bodies of water (e.g., the Ohio River or a large lake)?
4. How far do you need to travel and what is a realistic timetable for movement, whether in a vehicle or on foot?
Refine your estimate of the distance most likely needed to move. The experiences of backpackers, hunters, climbers, or infantry types are extremely important to pay attention to. Most folks seriously over estimate their ability to move anywhere carrying weight. Professionals have all learned (painfully) to carry only what is actually needed. No one is born with the expertise…it is taught and learned over a period of time, and paid for with blown out joints, raw feet, gastro-intestinal issues, and strained musculature.
I’ve spent all of my adult life doing the sneak around the countryside thing carrying a rucksack while other folks attempted to find me (in training) or kill me (when it was in someone else’s country). My rule of thumb in a generic “survival”, “social upheaval”, or “natural/man-made disaster” situation…a group of healthy adult males will be doing well to complete 12 miles in an average day or night of foot movement, while carrying moderate loads on their backs. This holds true whether for a patrol of Airborne Rangers, Appalachian Trail through-hikers, or mountaineers on an approach march. Even if you are walking alongside paved roads on level ground (walking along a freeway)…you will not make the ambitious distance that many envision in their heads.
Think about it. Even in a permissive environment (where law and order exists and some services are still available), people may still become temporary refugees. Whether stuck in massive traffic jams or reduced to walking long distances along man-made routes (roads, trails, streets, railways), you will be traveling the same direction as many other folks and for the same reasons. Friction will ensue. Some folks will want what you have. Some will get in your way and slow you down. Some will attempt to attach themselves to you despite their inability to provide supplies or resources. Some strangers may actively impede your movement or offer you violence. Groups of desperate people may eventually succumb to a mob mentality, triggered by some emotional outburst or the urgings of some would-be alpha male / alpha pair type. Competition for resources begins when folks run out of water, shelter, food, gasoline, and patience.
For planning of vehicle fuel and fluids (oil, coolant, winter wiper fluid), imagine a Memorial Day, Labor Day, or Fourth of July traffic jam. Remember or review the reports from the Katrina evacuation. Multiply the effect by a significant factor if there is an imminent threat. The ¼ tank of fuel needed for a normal trip to Grandma’s House might be burned sitting in a 50 mile long traffic jam or the off-ramp to a gas-station that just ran out of fuel, fluids, water, toilets, and food. In a dry environment, after a day or so without water, EVERYONE will move to the nearest perceived supply. "Waterholes" are dangerous places. Predators and prey gather at the same locations. It's not just something you watch on Animal Planet.
If the situation becomes semi-permissive (threat of mob or sectarian violence, breakdown of law and order, checkpoints, barricades, mass incarceration, or forceful evacuation by authorities), you might find yourself moving cross country, through cover or concealment (hills, forest, or brush) and along natural lines of drift (valley floors, ridgelines, or waterways). Moving across this type of terrain cuts your daily movement plan even further.
Herds move more slowly than individuals. You are not going to make 30 mile, 25 miles, or even 20 miles on foot accompanied by small children, loved ones of smaller stature or advanced years, or other out of shape companions. You will move as fast as the slowest link, no matter how dear to you that person is.
Add in blazing summer temperatures, pitch dark, freezing cold wind, snow, driving rain, sleet, or fog…and movement will drastically slow down.
Twelve miles per day with moderate packs (25-50 pounds) is a good planning figure for a group moving both deliberately and stealthily. Covering 4 mph on pavement with 45-60 pound rucks and weapons is a stiff 12-miles-in-three hour pace for trained infantry. At best, you are probably going to move half that fast and need rest breaks, chow breaks, and occasional security breaks to reconnoiter and figure out what is going on ahead of you (and whether you should change direction or go hide).
5. So…How long do you really need to live out of the contents? (See # 4 above)
You already indicated simply using the term “72-Hour Bag” as a general term familiar to readers and that you understand the reality might be more or less. Refine the timeline a little further to arrive at what you are actually going to carry.
If you simply intend to get as far away from trouble as quickly as possible, grab everyone, leave early with what you need for a hotel, and have plenty of cash and credit cards. Carry as much contingency gear, irreplaceable mementos, and personal/financial data as you can, but keep foot-movement BOBs light; everything else gets stored in the vehicle and is expendable (in case you have to abandon the ride).
If you need to walk home from work…say 5 to 40 miles…you need some backpacking and self protection type items to travel solo for a period of 1-5 days.
Longer term, if you need to abandon your home to rioters, flee your about to be mob-looted mini-van, or get ahead of some cataclysm…you need carefully parsed weights of critical outdoor backpacker items, some practical rehearsal time using it on hikes, and a plan for acquiring water after the first 5 days (rationed) and food after the first two weeks (rationed). You won’t be able to carry more than that on your back, even if you are carrying very little of anything else and pre-plan/package the weight and calories for every meal carried.
Thirdly: My minor suggestions to your list (I’ll mainly touch on things not already addressed by someone else)…
Mosquito netting – NOT SURE WHAT YOU ARE USING FROM YOUR PHOTO. SUGGEST USING A MOSQUITO HEAD NET PER PERSON; COMBINE WITH LONG SLEEVED SHIRT, PANTS, LIGHT GLOVES, & DEET…GOOD TO GO…FROM AFRICA, TO MIDDLE-EAST, DEEP IN THE JUNGLE OF PANAMA, SWAMPS IN FLORIDA, AND FIERCELY INFESTED ROCKIES. YOU DON’T HAVE TO SET UP A HOOTCH, TENT, SHELTER OR HAMMOCK BEFORE YOU CAN BE PROTECTED. SIMPLY SET BACKPACK ON GROUND, SIT DOWN TO REST, AND PLACE HEAD NET OVER HEAD.
Flare – Good for alerting traffic if you collapse under the weight of the pack on some dark road. LOSE IT. UNNECESSARY WEIGHT. MOVE OFF THE ROAD. IF YOU ARE BY YOURSELF AND COLLAPSE, HOW WILL YOU LIGHT IT? IT WON’T LAST LONG. GET A TINY LIGHTWEIGHT BLINKING RED LED MADE FOR RUNNERS OR PET COLLARS; ALTERNATIVELY A PETZL HEADLAMP WITH STROBE FEATURE.
Zip ties (25) – LOSE ‘EM. WHO ARE YOU GOING TO CAPTURE? THEN WHAT?
Folding shovel – JUST KEEP THIS AND/OR A SNOW SHOVEL IN YOUR CAR. A FOLDING E-TOOL IS TOO MUCH WEIGHT IN YOUR PACK…UNLESS YOU ARE EXPECTING TO CONSTRUCT FIGHTING POSITIONS OR FOXHOLES WITH OVERHEAD COVER. GET ONE OF THE ORANGE ABS BACKPACKER TROWELS FOR CARRY IN THE BOB. TROWEL WILL SUFFICE FOR HOLES TO POOP IN, CACHES, ETC. THEY WEIGH ONLY OUNCES AND ARE DAMNED NEAR INDESTRUCTABLE.
http://store.everestgear.com/159070.html
Sleeping bag – YOUR INCLUSION OF A COLD WX BAG SUGGESTS THAT YOU LIVE IN A WINTER ENVIRONMENT. I HAVE ONLY A FEW SUGGESTIONS FOR YOU: GO WITH A BAG RATED FOR THE LOWEST TEMPERATURE POSSIBLE (AT LEAST 0 DEG; -15, -20, ETC IS BETTER). BAG MANUFACTURERS ARE NOTORIOUS FOR EXAGERATING THE COMFORT LEVEL OF THEIR BAGS. IF YOU FIND YOURSELF IN A WINTER BOB SITUATION, THAT SLEEPING BAG IS PROBABLY WAY, WAY MORE IMPORTANT THAN THE SCAR. BUY QUALITY, BUY MAX INSULATION VALUE, AND GET A BIVY SACK TO PROTECT THE BAG IF YOU EXPECT WET COLD, RAIN, OR FLOODED/GROUNDSOAKED CONDITIONS. IN FACT, BUY A GOOD GORETEX BIVY SACK ANYWAY. A WET BAG IS A DOOMED NIGHT OF SLEEP AND POSSIBLE DEATH. YOU ALSO NEED TO GET SLEEPING PADS (ONE FOR EACH SLEEPING BAG). ANY CLOSED CELL FOAM BACKPACKER PAD WILL DO. PREMIUM RIDGERESTS OR SELF-INFLATING THERMA-RESTS ARE NICE, BUT THE SIMPLE FOAM ONES THEY SELL IN WAL-MART WILL WORK JUST FINE. STAY AWAY FROM AIR-MATTRESSES LIKE THE PLAGUE. THEY OFFER ZERO INSULATION FROM THE FROZEN/WET GROUND AND WILL PUNCTURE, BECOMING USELESS. INERT CLOSED CELL FOAM IS THE WAY TO GO IN A LIFE OR DEATH SITUATION. THE BIVY SACK, THE PAD, AND THE SLEEPING BAG COMPRISE A SYSTEM…EACH IS A LEG ON THE STOOL. YOU NEED ALL THREE. DOWN BAGS ARE STILL THE GOLD STANDARD FOR ABSOLUTE INSULATION VALUE AND LIGHTEST WEIGHT/BULK, BUT SYNTHETIC BAGS RETAIN INSULATION VALUE WHEN DAMP/WET AND ARE A LOT CHEAPER. FOR TOUGH CONDITIONS IN CHANGEABLE WEATHER AND SETTINGS (RAIN & WET SNOW), GO WITH SYNTHETIC FILL. REI’S WEBSITE HAS A PRETTY DECENT SELECTION OF BAGS AND WEBSITE INFO ABOUT BAG SELECTION.
Crowbar – Just in case the shovel wasn’t enough dead weight.
wrench can turn off gas mains, break into houses and cars if need be. yes, it's heavy. force = mass X acceleration. THIS IS A TOOL FOR YOUR CAR, NOT YOUR PACK. REALLY, REALLY USELESS WEIGHT WHEN WALKING. I’D KEEP THE SHOVEL BEFORE THIS. YOU COULD CARRY A SMALL 6” -7” PRY BAR INSTEAD TO OPEN DOORS, WINDOWS, OR LOCKS.
http://www.amazon.com/Stanley-55-045-7-1-2-Inch-Wonder/dp/B00002X1XS
Caffeine mints – ALSO CAFFEINE GUM. GOOD STUFF WHEN YOU ARE TIRED BUT NEED TO STAY AWAKE OR ALERT. OR ARE CRAVING A SMOKE BUT CAN’T (DUE TO SECURITY ISSUES).
Handcuffs – LOSE ‘EM. EXCESSIVE WEIGHT. REALLY. UNLESS YOU ARE PART OF A PURPOSE ORGANIZED ASSAULT FORCE OR CONDUCTING LEO DUTIES…YOU DON’T NEED TO BE WORRIED ABOUT RESTRAINING FOLKS. IF THE SITUATION AND SOCIAL ORDER HAVE DETERIORATED TO THE POINT WHERE YOU DO…YOU DON’T NEED TO BE BRINGING DETAINEES ALONG WITH YOU ANYWAY.
Towels and rags – LOSE ‘EM. IF YOU ABSOLUTELY HAVE TO HAVE ONE…HAVE JUST ONE. ONE SMALL TERRY FACIAL TOWEL WILL SUFFICE FOR TOILETRY DUTY AND DRYING OFF OF FEET. BTW: YOU SHOULD ADD IN SOME ANTI-FUNGAL FOOT/CROTCH POWDER TO YOUR LIST (GOOD TO APPLY TO RECENTLY TOWELED PARTS OF THE BODY).
Smoke grenades (4) – LOSE ‘EM. I DON’T EVEN CARRY FOUR SMOKE GRENADES IN COMBAT. EXCESSIVE WEIGHT FOR YOUR PURPOSES AND ONLY IMAGINARY RETURN ON USEFULNESS.
Bic lighters (10) – 2 IS ENOUGH…NOT 10.
Water (4) – Fragile bottles, four times the chance for one of them to leak onto your sleeping bag. USE 1 QUART OR 1 LITER CANTEENS OR NALGENE BOTTLES. LITTLE PLASTIC 7-11 DRINKING BOTTLES WILL BREAK JUST WHEN YOU REALLY DO NEED THEM OR NEED TO REFILL THEM MULTIPLE TIMES. TRUST ME. ALTERNATIVELY, GET EVERYONE 3-LITER CAMELBACK-TYPE HYDRATION BLADDERS.
SCAR – YOU APPARENTLY ALREADY OWN ONE. IF YOU WENT AR-15 FOR THE OTHER THREE, YOU COULD APPLY THE MONEY SAVED TO BUY DECENT BACKPACKS, TENTS, SLEEPING BAGS, AND BIVY SACKS. NOT TO MENTION HIKING BOOTS AND QUALITY WHITE GAS BACKPACKER STOVE (LIKE MSR MULTI-FUEL WHISPERLITES). ALSO WHITE COMBAT LIGHT AND MOUNTS FOR EACH RIFLE. FOR THE SHORT DURATION, 3 X MAGAZINES CARRIED SCENARIO YOU’VE DESCRIBED, WEAPONS COMMONALITY IS IRRELEVENT.
Hope this helps.
Walking sounds like the order of the day. 
