When I first left the Army I was a lil fed up with society in general... one day I was driving through a small Oregon Rural town called Willamina , in my 71 blazer was a S&W mod 66 2 loaded speed loaders and a box of 50 rounds of Hornady 125 XTP Custom, a hilift jack, 2 BDU coats, a sleeping bag, a machete,an axe, folding shovel, first aid kit, on the tailgate was a spare tire carrier with a spare 35x14.50 Wild country tire, 2 5 gallon watter cans, 2 5 gallon gas cans that were full, I had a small duffle bag with 2 pair of wranglers, 2 underwear, 4 pr socks, 4 t-shirts, 2 BDU shirts, 2 BDU pants....
on a spur of the moment thought I detoured off road on an old long abondoned logging road and drove until I could not get get up one last dirt bank I was exactly 27 miles in from any recent trace of people...... I lived in the Blazer for 6 months without leaving a 10 mile radius from the Blazer....... the first night as it got dark while I was 4 wheeling in I ate snacks that were in the truck, the next morning I back tracked and obliterated sign of my trucks passage through the woods up the mountain.... on my way back to the truck I shot a doe (yea poaching) with the .357 and packed it back to the truck...... over that 6 months I lived off squirles, rabbits another couple deer, the temps ranged from snow to hot and humid with rain most of the time.......
A few years ago I did the same thing here in the AZ desert with only a few modifications one being no truck as I hiked into a very remote area after having my EX drop me off on the side of the highway, I took 1 AK Yugo M70AB2, 12 loaded 20 rnd mags (240 rnds) 200 rnds on strippers in a chicom chest pouch, a Springfield Armory XD 40 Tactical 3 mags and 100 rounds in reloaders box, 2 folding knives, 2 BDU shirts, 2 BDU Pants, 4 t-shirts, 4 shorts, 4 pr socks, an ultralite hikers tent, 5 lbs of rice and beans mixed, 2 1 quart water bottles mummy sleeping bag a field kit and assorted first aid supplies, 2 100' repelling lines and roll of 1" webbing, topo map, cell phone in an alice pack........ I evaded the border patrol hiking into the mountains along the USA/Mexico border evaded smugglers and illegals had a few tense situations, stayed out 4 months living on rabbits, javalina, snakes/lizards............. why? to see if I could still do it
I live 10 miles from the end of a road nobody else has any reason to drive down, at the end of that road is pure un molested desert within that area is plenty of water and game if ya know where to look, indians lived out there for centuries with far fewer supplies than My bugout pack contains.......
As far as the poster asking how far ya can hike while carryin a full double combat load........ about 20 miles per day in 100 degree heat while evading the US Border patrol and all of their arial and ground stationed recon equipment and personel........ I make a point in my day to day life of not drinking more water than my body must have, I work with my hands welding or whatever else needs to be done everyday, eat once in the morning and again before I go to sleep usually, I don't let myself become dependent on extras, have no family and as my GF is a border patrol officer who thrives on us taking day hikes that usually turn into overnighters out into the desert..... between the two of us we'd have no problem getting outa here, the area up the road is littered with abandoned mines from the 19th century, I have resupplies stashed in many of them, extra firepower, ammo, food and other supplies........
As far as the OP, how much YOU can carry will depend totally on YOU and how you live every day, ya mention that ya were never in the military and have no experience there etc...... well unless ya have spent most of your life training and conditioning then your best option is not bug out but bug in and hope for the best as a disaster scenario such as ya described will not go well for you regardless how much ammo or what kinda gun ya carry....... the gun plays a very small role in a survival situation, out here in the desert smugglers are the biggest threat and if they know your there they will try to take ya out (the reason I took the weapons/ammo I did on this trip versus the situation up in Oregon, there was a good possibility of a prolonged fire fight if discovered where they would be armed with automatic weapons and seriously need me dead to avoid getting busted I was fortunate and went un detected as I trailed many of em over that 4 months..... the key is not being seen and not being seen means not leaving any trace that ya were ever there.... the physical conditioning and skills needed to survive a situation as ya describe is not something ya can start at the 11th hour but requires a lifetime...
if you are dependent upon stores and piped water then your pretty much screwed in an end of the world scenario as ya describe in your original post, I grew up on a Rez in SD and have spent my entire life in the country working stock, hunting, fishing and camping and no my idea of camping does not include any vehicles or modern conviences, just what ya can pack on your back...... to determin what YOU can carry ya gotta start with a very honest appraisel of your lifes experiences and what ya have learned from those experiences what skills have those experiences supplied ya with? what kinda physical condition are ya in and how accustomed to physical labor is your body? How dependent are ya on modern conviences? cause ya see when these things are suddenly gone there absence will greatly effect your ability to cope..... rendering ya nothing more than a walking (or deceased) ammo/weapon resupply for those of us who have spent our lives making a point of not becoming dependent on those modern conviences etc..
As far as open carry as mentioned by someone in CT....... Southern AZ it is not an uncommon sight to see folks packin EBRs across their backs or strapped to saddle bags of Harleys..... cops out here don't give the sight of a long gun or handgun or even Machine gun much thought.... thats the effect of a truly open carry state which has never prohibited or regulated the open carry of firearms