Some thoughts...
I was born in the last great decade, the 50's. Take into consideration this time in history if you will, as to what had occurred, and what would occur.
Before JFK was shot in '63, before the GCA of '68, a real concern was - gun control. Again, look at history, and the restrictions around the world.
Mentors were concerned if the US ever had "restrictions" that denied anyone to have "guns, calibers and gauges, the Police & Military use".
Some countries do have this restriction and have for a long long time.
i.e. the populace cannot have 9mm, so they do .380 or 32ACP.
12 gauge is used by Police & Military, world over. So what does that leave J.Q.Public?
Now even before non-tox became a concern for Migratory Waterfowl, the concern was an alternate material for projectiles to replace lead.
I am dead serious when I share a lot of the Veterans of previous Wars, used .410 and 28 ga guns, in the locales I was raised in, and frequented.
Injuries, and add age. Just toting a gun was difficult for some, especially when there was more toting than shooting to be done.
The 28 ga is .550, which is not far from being .54 caliber, which has a historically proven record for felling two legged and four legged critters.
I have mentioned the 28 ga slug numerous times before. Yes, it exists today, as it did in yesteryear, and yes it will still fell a deer today and it did in yesteryear.
Ducks- Many prime hunting areas "restricted" one to using 28 ga or smaller shotguns. Bing Crosby is one such famous Actor and Performer, whom restricted his friends, on his hunting property to to 28 ga or smaller.
Take a look at some of the gun control , or restrictions that are on the books.
Pay attention to definitions, as some of these are "open" to being interpretated according to the whims of Tyranny.
Words such as "repeating", and "capacity" for instance. If...If the USA ever chooses to "push it" if you will, just interpretation what is already written could work against J.Q. Public.
Police and Military use 12 ga, with short barrels, and magazine extensions.
Some are pump, some are semi autos.
This is why I and others have insisted folks not only have Software first, they also include having some bone stock "hardware".
I have nothing against black, synthetic stocked shotguns with mag extensions and side saddles. I do have a problem with folks believing they can buy such guns and magically evil will not bother them, and if evil should choose to, these guns would magically handle the situation.
I do want choke in a shotgun barrel, for even a Cyl bore has a point or two of choke.
Ireland if memory serves, restricts J.Q. Public to a shotgun barrel no shorter than 24".
So instead of whacking off a really fine barrel, with fixed choke, that really is a better barrel being made today, and patterns so well and ending up with a shotgun that will not pattern worth a flip...
One would be wise to find a shorter barrel that would fit that gun.
It would be better to have to turn in a good used short barrel, than a shotgun, or end up with a shotgun with no barrel and having a devil of a time finding a longer barrel to fit it.
Take a look at the gun control and restrictions other countries have. The same playbook, with reasons are being used in the USA.
Current knife laws imposed here in the USA, are being imposed using the same thinking, reasoning and marketing used by other other countries that imposed such laws.
So, what if the USA says you can still shoot 3 gun, but the gun has to be locked up at the range, or local "police" station as some countries do. What if one is required to get a special permit to have such a gun, and part of the requirements is , you must participate in so many shooting events a year?
What if the USA says the local police will have to approve you and your setting to make sure you have an approved locking container, and the shotgun and ammo have to be separated, in different , approved, locking containers?
One will have two required inspections, and one may be subject to random inspection?
One can get a single shot, or double shotgun loaded up faster if serious should come to visit.
Especially if the tactical 3 gun is locked at a range or police station.
Mentors shared having hulls, wads, shot, powder and primer, especially primers, when putting back reloading supplies.
Bismuth...was something back then and applies to today in looking at a viable alternative to lead.
Smaller gauges use less "projectiles" which includes less weight for slugs.
How would one make their own bismuth pellets, or slugs?
One half ounce payload for a 410 bore, and three quarters of an ounce of payload for a 28 bore takes less pellets, than the payload for a 20 or 12 bore.
That might be a good questions to investigate and verify, along with sticking back reloading supplies, instead of trying to keep up with TEEM SEEL, and IAMBAD SWAT.
20 bore is a fine bore.
Some years ago I was in a large chain of sporting good/outdoor store, and had already bought all the Brenneke 12 ga, 2 3/4" they had. I had them order some more by the case.
I had already bought all the 20 ga 2 3/4" five packs of these Brennke's as well
I asked if they would call me when they got another order of the 20 bore, in, and asked if I could add buying 500 more.
I and mine were willing to pay up front. The person said, 250 total would be more acceptable, simply because they were going to change distributors, as the prices were better, so this was going to be the last order from that source.
I said fine, as I understand business and all.
The person called, and right off apologized, because I was only going to get 10 , five packs, of the 20 bore Brenneke's.
An Air Force Base had ordered 500 20 bore Brenneke, along with a slew of #3 Buckshot.
Due to training I was told , they needed the 250 I had ordered.
I was nice, said I understood and we worked out the money end, as I and mine had paid up front.
My gut felt real uneasy, about this. One of the gals in this buy asked me why I felt funny.
Simple, if the restrictions ever say J.Q. Public cannot have what the Military use[d] then there goes the 20 ga as well.
There was a reason Mentors not only hoarded certain firearms, calibers, gauges and such.
I know some members here using .410 and 28 ga for a lot of their hunting, including deer with slugs from a 28 bore.
I personally have felled a slew of ducks with 28 ga, along with doves, quail and other small game.
Yes, I have taken deer with 28 ga slugs, and used those slugs for property and pest control.
Yes, a load of #5 hard shot, will fell a turkey as well.
Just some software thoughts, from my life and experiences.