Originally based on a USAF aircrew survival rifle. Trigger was originally w/o a guard, and designed to be used by mittened hands.
The trigger guts will greatly benefit from a dis-assembly, cleaning, and proper lubing. An educated person can smooth the engagement surfaces on the TG, and this will always be to the good. The factory offered an OEM sight rail that mated with pre-drilled holes in the receiver, but long extinct. This can be duplicated by your gunsmith.
Full choke on a .410, for a survival rifle makes some sense, being most likely to harvest small birds/game. Downed aircrew using such a gun, with minimal practice probably would not benefit from slugs, and would benefit from shot fired from full choke barrel. Trade-off, favoring the most likely users.
As with all .22s, find a good ammo that it likes, and stock up. Dial-in the iron sights at appropriate (short) range. Paint rear of front sight blade with neon green luminescent paint for quick sight pick-up under any conditions.
Older eyes will benefit from various sorts of optics, as the OEM iron sights are crude. This makes a rail installation mandatory.
I detest rounds added to slings, as they greatly interfere with swinging the weapon freely. Worst thing ever.
The .410 SG barrel can be augmented with rifle-barreled inserts from MC ACE, and that expands one's horizons greatly.
http://www.mcace.com/adapters.HTM
I had no idea that these things were currently worth so much.
I have mine stashed in a nylon camo case originally made for Savage 10-24 rifles.
One thing I did almost by accident, was to buy a QD take-down pin for it at a local ship's chandlery. It's a stainless steel pin, of correct diameter, with a flared, tulip shaped head, with a push button recessed within the head. Push the button, and withdraw the pin holding the rifle together; instant dis-assembly. IIRC, later rifles came with something similar, but my rifle had a pin with E clips. Now, I have a take-down.
Hmmmmmmmmmmm. Maybe I should sell mine.