Red, I'm still drooling over your suppressed .410 Mossberg since the first time I saw it. As easy as guns are to get here, something that is a real hassle to get in the US is a silencer. It is a $200 transfer tax over the cost of the silencer plus it takes about a year nowadays to get the Federal paperwork processed. So, you have to buy it, pay the tax, then wait for approval. You should always also carry a copy of the tax stamp paperwork with you when transporting and using the silencer. Only 36 states allow them, and only a very few just started allowing them for hunting, with one of those being Texas.
The .410 I'm using the most nowadays is the .410 subcaliber adapter I use with my 12ga pump Mossberg. I have a dedicated .410 that is a real game getter, an ancient Winchester model 37 that has a full choke on it (.375"). However, the Mossberg is much more versatile and almost indestructible. It also stores more compactly when I need it too due to easy barrel removal. The Winchester doesn't break down quickly and easily like other break actions often tend to do, like an H&R Topper, for example. So when I toss a long gun into the jeep or the boat, it's invariably the Mossberg. However, the old Winchester is a joy to shoot and it makes the most out of what a .410 can do.
The .410 adapter actually gives a pretty good spread at closer ranges. Needless to say, there isn't any choke to the pattern. It's kind of like a .410 blunderbuss, but it works on cottontail rabbits. Essentially, I jack back the pump slide with the barrel pointed down, drop in the adapter with a .410 shell in it into the ejection port and down into the barrel, then close the action. It works great. The smaller kids also like it due to the much lower recoil and so I'll also use it in shotgun instruction courses with some of the students
Extraction of the adapter happens just like a standard shell, only with a pump you have to make sure you don't fling the adapter like spent plastic shell, so you eject it mildly. I usually eject it right into my hand. With a break action it's a simple affair. Getting the spent shell out of the adapter is never a chore, just bump the tip of the open end of the spent shell with a fingertip and the base pops right out.
On my 12ga Mossberg I have a buttstock pouch with a .410 adapter, a 20ga adapter, and a 2-3/4" rifled .22LR adapter. They store inside the pouch in standard 12ga shell loops.
The 20ga uses standard length shells, which is the vast majority of the 20ga ammo you will find here. The .410 adapter is a bit longer and can use full length 3" shells, which are usually the most commonly available here. There are several models available, the .410 and 20ga adapters I use are both from different manufacturers and were $25 each, while the rifled .22 adapter was $60.
The .410 adapter can also fire a .45 Colt pistol cartridge. The .410 has it's origin as a .45 Colt shotshell, hence the chamber compatibility (of course we all know that one should never fire a .45 Colt out of a .410 with a choke). However, I don't bother with .45 Colt ammo since it's a smoothbore and accuracy with a .45 Colt round with it is dismal at any meaningful range. For anything I would use that for I can just use a 12ga slug or a .22LR round.
The 20ga adapter works well, with a decent spread. It'll bring down quail. Of course, there is no choke on it either.
The rifled .22LR adapter is surprisingly accurate, enough to hunt small game with at 40 meters. How that works is the bore is offset so the centerfire firing pin on the shotgun strikes the rim of the rimfire cartridge. For consistent shot placement you should 'index' the adapter so the offset bore is either high in the chamber or low in the chamber. It'll fire any rimfire .22 ammo, including the 6mm Flobert BB cap roundball and a .22 pellet fired with a .22 blank round like they use in nail guns (the ones I've used have been the Remington yellow tip). A .22 pellet is a tad smaller than the bullet in a .22LR (IIRC it's .221" for the pellet and .223" for the .22LR though that can vary with manufacturer), so a small ramrod to push the pellet into the beginning of the rifling before inserting the blank is a good idea. The best accuracy though is with standard high velocity .22LR solids or hollowpoints. You remove the spent cases with your fingernail.
Using the pump is a trade off, since I can only use chamber length adapters (3" chamber). With a break open you can use longer adapters. Some adapters in shotgun gauges have their own extractors/ejectors. I found out through trial and error that one company, Short Lane, makes their rimfire adapters with an offset measured to only work reliably with the typically wider firing pin of a break action vs the typically more narrow firing pin of a pump (it seems they did it to save a couple of machining steps).
In case anyone is curious about the models I'm using:
.410 adapter
http://www.gunadapters.com/
20ga adapter
http://shotgunadapter.com/
Rifled .22LR adapter
http://www.gaugemate.com/