​While most armies soldiered on with bolt action relics of World War One, World War Two America enjoyed the advantages and disadvantages of the M-1 Garand. The chief problem was in production quantity. America enlisted sixteen million into its armed forces in World War Two and did not complete five million M-1 rifles until 1955. M-1’s in .30-06 were supplemented by two million 1903-A3 bolt actions, six million M-1 Carbines (much smaller cartridge) and two million M1A1 Thompson submachine guns in .45 ACP. The US Ordnance department wanted a new design to replace the pistol, M-1 Carbine, Thompson, M-1 rifle and Browning automatic rifle. Ambitious?
 
General George Patton promotes the German assault rifle StG (Sturm Gewehr/Assault Rifle) 45 (1945) to replace the M1 Carbine, M1 rifle, Thompson submachinegun and light machinegun/Browning Automatic Rifle in infantry squads. StG 45(M) - Wikipedia The .280/7mm British cartridge gives adequate trajectory and impact past the 300-yard engagement range of the average infantryman. Because the .280 British is longer than the Nazi 8X33mm Kurz, the design must be modified, delaying mass deployment. .280 British - Wikipedia The assault rifle is easily mas produced with a pressed steel receiver and weighs eight pounds. The detachable magazine fed assault rifle accommodates an infrared (IR) Sniperscope and has the range to utilize post WWII advancements.
 
The Soviet Union ‘independently’ came up with the cartridge M-43 7.62X39mm after experiencing attack from a new German carbine in 1942. Eight-pound Simonov 45 carbines appeared in time for the battle of Berlin. The Simonov is a gas operated semi-automatic carbine with a fixed ten-round magazine. It is reloaded through the top of the action by ten round stripper clips. The Simonov’s had machined receivers and wooden stocks well within Soviet wartime technology.
 
The AK-47 was designed shortly after WWII with a stamped and riveted sheet metal receiver much like the MP-44/StG-45. The stamped receivers came apart under use until better Russian steel made the AKM possible in the 1960’s. A machined steel variant AK-49 worked okay and accompanied Soviet troops to Hungary in 1956.
 
Patton’s paratroops are armed with 5.5-pound M1 carbines. The M1 carbine weighs half as much as the World War Two M1 Garand rifle. The cartridge is far weaker with a 110 grain bullet at 2000 feet per second versus 150 grain at 2700 fps for the M-1 Garand rifle. The M1 carbine is loaded from the bottom with a ten or 15 round detachable box magazine. This means an infrared (light) Sniperscope can be placed over the action without hindering loading or overburdening the soldier. Nazi Germany fielded small numbers of the infra-red Vampyr device and used them to defend Tiger Tanks from Soviet sappers.
.
American infrared sniperscopes were notably effective in defense against Japanese night attacks on Okinawa where the effective range of the Carbine and sniperscope was 75-yards. Sniperscope/Snooperscope: Use During WWII - The Carbine Collector's Club (uscarbinecal30.com)
 
The 1,200 round per minute MG-42 was built for the 8X57mm Mauser cartridge and was not adapted to the longer .30-06 cartridge successfully. It was no problem to chamber the stamped metal MG-42 machinegun to .280 British. The MG-42 Machine Gun | The National WWII Museum | New Orleans (nationalww2museum.org) I have had the pleasure of firing the MG-3 descendent of the MG-42 from the prone position.
 
Army Ordnance is looking for a lighter pistol cartridge and pistol. The .45ACP cartridge weighs as much as the .30-06 rifle cartridge and has just 100-yards effective range in the Thompson SMG versus 500-yards for the .30-06 rifle. Odds on favorite is the 9X19mm Luger (now NATO) used by England, Canada and China as well as Nazi Germany. The 9mm weighs half as much as the .45 ACP.
 
Patton grew up with .45 caliber pistols that worked well in the Philippines’, World War One and World War Two. Patton advocates a compromise .40 caliber that will fit existing 9mm pistols and give adequate stopping power with a flat point bullet. The Canadian built P-35 is modified for the slightly larger caliber. The U.S. Army soldiers on with the .45 ACP 1911A1. The P-35 in 9X19mm Luger is adopted for airborne troops.
 
Soldiers in trenches are difficult to hit with rifle fire over their heads. Hand grenades can be tossed into foxholes by any soldier able to advance past machineguns. The mortar can drop bombs into trenches and machine gun nests from hundreds of yards away. Having mortars light enough to advance with the troops saves time and radio bandwidth. Not to mention that annoying short falling friendly fire. 
 
The US Army experimented with a light 60mm mortar before World War Two that relied on the skill of the user to estimate range and angle of fire. That didn’t work well and adding a tripod and baseplate brought the weight up to sixty-pounds. Not so portable.
 
Before World War Two, both the French and Japanese invented 50mm mortars weighing ten pounds and using a fixed firing angle. The French relied on a leveled baseplate with the firing angle controlled by a chain. Okay, if you have time to level the baseplate. The Japanese knee mortar uses a concave baseplate that instantly adapts to varied terrain. One was issued to each infantry squad and carried along the thigh of the user. Angle was held constant with a built-in bubble level while range was controlled by screw-adjusting the barrel length. Okay, if you can see the bubble level. Good place for radium paint. The British used two-inch mortars on armored vehicles in World War Two and later to dispense smoke. Type 89 grenade discharger - Wikipedia
 
The 3.5-inch, 90mm, super bazooka M-20, was designed to defeat Nazi Tiger tanks in the waning days of WWII. The shaped charge warhead can penetrate eleven-inches of armor at any distance. Most users can hit a tank at 100-yards. The aluminum tube version weighs only eleven-pounds and the tube can be hinged for paratroop deployment. While the anti-tank artillery of WWII weighed several tons, the M-20 can be fitted to a Jeep or VW kubelwagen. The historic US Army dropped this weapon until needed in Korea against the T-34/85.
Recoilless rifles use a massive jet of propellant gas to the rear to counter the recoil of launching a shaped charge (HEAT) forward at 1,000 feet-per-second. Good shots can hit a sitting tank at 1,000 yards. The same rifling spin that stabilizes the shell in flight destabilizes the shaped-charge liquid metal stream on contact. Armor penetration of the 57mm M18 RR is about three-inches while the 75mm M20 will penetrate 4 to 5-inches and was effective versus the T-34/85 in historic Korea.
General Patton promotes shaped-charge High Explosive Anti-tank research to improve the 105mm howitzer performance to equal the 90mm tank gun.
Factors to try are standoff distance between contact fuse and shaped charge, explosive (TNT vs RDX, HMX), Cone angle, Cone/liner material (steel, copper, depleted uranium). Depleted uranium is used for tank sabot rounds, today. Experiments have found depleted uranium rock-drilling charges give three-to-five times the penetration of copper charge liners. Penetration of an optimal depleted uranium liner of a shaped charge: A numerical simulation method - Rongzheng Xu, Li Chen, Jinhua Zhang, Hengbo Xiang, Qin Fang, 2021 (sagepub.com)
A historic idea (1959) was to impress the liner of the 57mm recoilless with counter-rifling, increasing penetration to between four and five-inches. US3726224A - Fluted liners for shaped charges - Google Patents

​Able bodied citizens should own firearms for defense of themselves, their families and their country. Naturalized citizens, male and female, vow to take up arms to defend the United States and Constitution. Selective Service says males have an obligation to serve when called.
Two evacuations, a home burglary and advancing years have me examining my firearms in light of what I might reasonably evacuate with and leave to my heirs. Firearms can last for centuries. Some have fired cannon-lock wall guns from Tannenberg Castle THE TANNENBURG GONNE .75" BORE (handgonne.com). Firearms may be made of rust-resistant materials with chrome lined barrels and durable finishes. Firearms made in the millions may have the bugs worked out with replacement parts and knowledgeable gunsmiths widely available. Some designs are inherently less likely to cause problems for decades. As an extreme example, a science fiction author suggested the .75 caliber Brown Bess flintlock as a survival weapon for stranded space travelers. A modern flintlock rifle with .50 bullets would equal penetration with greater accuracy. A synthetic or aluminum ramrod won’t split or stab your hand. I haven’t owned a muzzle loading rifle, but include this thought for worst case scenarios.
Guns can be used for effective defense. Most events resolve without a shot being fired. I have only fired one shot with intent to save a life. It was a warning shot into the ground which stopped a big man slamming his girlfriend’s head against a concrete sidewalk.  Otherwise, there have been a dozen times I was glad to have a firearm available (about half with animals in camp, at night).
Handguns leave a hand free to open a door, hold a flashlight, cellphone, or child; or fend off an attacker with bad breath. Pocket guns don’t gain attention by criminals or police. The neighbor who knocked for sugar at midnight wasn’t terrified by the gun hidden in my robe pocket. She was making a cake for her son’s birthday even though we both worked swing shift and stores weren’t open (yes I was around when 7-11 were the store hours).
A handgun may be secured in a locked drawer. A double-action revolver may be loaded/un-loaded and cleaned without cocking the hammer. Revolvers can rest loaded for decades without any springs under tension to weaken or fail. Metal parts can break from metal fatigue when under spring tension for decades. Revolvers are usable with cartridges having a great variety of bullet nose shapes and power levels (.38/.357 Magnum). Revolvers retain the cartridge case which makes reloading easier.
American ammunition factories made only military ammunition during World Wars One and Two. You may want to store a five-year supply to get you through. Ammunition made today should be good for 50-70 years with dry, room temperature storage. After losing my stockpile, the recent ammo shortfall left .22 Long Rifle, 12-gauge shotgun and NATO ammunition (9x19mm, 5.56X45mm, 7.62X51mm) on store shelves. Over a dozen nations make NATO ammo for their own use so those factories geared up for export to the USA.
The FBI rates the 9mm, with expanding bullets, equal to larger calibers against humans. I’ve also read it works against bears. I have fair confidence in availability for the next fifty-years. 9mm revolvers usually require a sheet metal ‘moon clip’ to facilitate ejection and loading. These clips may be lost or bent out of reliable shape. A springy moon clip can defeat a firing pin. The 22-ounce Charter Pitbull uses spring loaded extractors to eliminate the need for clips. Model # 79920 | Charter Arms (charterfirearms.com)
Other revolver calibers to consider are the .22 LR (Long Rifle), .22 Winchester Magnum Rimfire, .38 Special/.357 Magnum and .45 Colt. The .22 LR is least expensive, lightweight, and available BUT is a less reliable stopper for humans or bears. Reloader’s may favor the .45 Colt designed to be a man and horse stopper with flat-point lead bullets and black powder. Charter Arms made a five-shot, 22-ounce, .45 Colt pocket revolver (not on the California roster). CHARTER ARMS 74530 BULLDOG XL .45 LC 2.5IN Stainless Steel FS | Guns Warehouse
Rifles generally give better accuracy than handguns because of a longer sight radius and four points of contact. .22 LR rifles are reputed to be reliable stoppers for people within 100-yards. Browning makes the nice SA22 takedown. The newer Savage A22 features detachable rotary magazines for quicker loading and unloading. The .223/5.56 NATO is used by police and military and has low penetration through apartment walls. The .308 Winchester/7.62mm NATO should be available for decades of heavy duty. Iron peep sights are fairly easy to use. You just look through the little hole and put the target on top of the front sight. A 9mm folding carbine can weigh just 4-5 pounds and fit in a backpack or dresser drawer. New: Smith & Wesson 9mm M&P FPC Folding Carbine :: Guns.com
It has always taken years to arm our troops for a major war. The Viet-Nam War saw us field a new .223 rifle with only .30 caliber cleaning rods in country. The designed-for ammunition wasn’t supposed to require cleaning in a dry temperate climate (or Siberia). The Army save some bucks by recycling poorly stored World War Two powder that filled the receiver with limestone fouling. You may want your own rifle. How And Why The M16 Failed In Vietnam (And Is It Reliable Today?) - Pew Pew Tactical
I don’t own forty-acres or a mule and couldn’t evacuate with them. My emergency food plan is to hunt large animals. Rifles work best for that.
I now prefer takedown long guns to avoid theft and avoid notice when going to a hotel room or traveling by bus, rail or foot.  Also, take-down action guns allow cleaning from the breech without ruining accuracy by scraping the rifling crown with the cleaning rod. 7 Salty Takedown Rifles For Any Survival Situation - Gun Digest When my longarms don’t take down easily, I have used folding chair sleeves to disguise them while moving.
Shotguns shoot heavy shells (9/pound) at close range. 12-gauge is available and is a reliable intimidator as well as stopper. Remington pumps used to be reliable but since the 2020 bankruptcy the current batch has problems with reliable extraction and ejection. Los Angeles police found semi-automatic shotguns can be fired from the prone position when rioters are shooting back at you. The quiet Metrogun extension Metrogun can minimize those pesky flash mobs when poaching. Otherwise, you can hunt during storms. Hammer shotguns, like revolvers avoid metal fatigue with the hammer down. Single shot break-open shotguns are about $150. Hammer doubles are $500. They clean from the rear of the barrel and takedown to fit backpack or suitcase with 18-20-inch barrels.
Rick