So for a long time I've considered a rifle I could put into a travel bag for road trips in case SHTF along the way (riots, gangs, whatever). As a size reference, something like a small suitcase, but not carry-on sized and packed with normal clothing.
Caveat is it cannot be a SBR.
So, I've been considering the following:
M1 Carbine (paratrooper)
CZ Scorpion
PS90
Nothing
My initial thoughts:
1) 30 Carbine -
a) Obviously the 30 carbine has the most power of anything on my list, and whilst maligned for "lack of stopping power" the ballistics at < 100 yards do not pan that out.
b) If I was comfortable with a "new" Inland or Auto-Ordnance I may be in; that said, I hear their reliability is awful. Then I could go the Fulton Armory route for major $$.
c) 30 round magazines may or may not be reliable.
2) CZ Scorpion (V3)
a) downside is it shoots 9mm, upside is they are available
b) have the looming "is it a SBR question hanging over them."
c) not much improvement over typical handgun
3) PS90
a) SHORT, very short with full length 16" barrel. (again, no SBR).
b) 50 rounds. But, 50 rounds of what more reliable 22 WMR?
c) Different manual of arms with the magazine.
4) Do nothing, buy more ammo.
You COULD look at the Kel-tec CMR30, I have one, a lot of fun and with the right .22 WMR load, not a bad choice. The stock collapses and is very compact. It comes with two 30 round mags, you can get a pistol to match, they share magazines.
The trigger in mine is unbelievably crisp.
The CMR30 .22 Magnum carbine holds 30 rounds in two flush fit magazines. It's portable, reliable, and versatile, with plenty of firepower.
www.keltecweapons.com
Our department has a couple of scorpions, they are a blast, definitely more accurate than a handgun, but a bit bulky. The triggers suck, which is weird, I'm the resident CZ fan boy and the triggers in their handguns are pretty damn good, don't know why the scorpion triggers suck, but they do. we got them for covert carry in a backpack, they work superbly in that role.
The problem you are going to have with the scorpion is this: if you get the pistol with a brace, is it going to be classified as an SBR?
If you get one with a stock, it is an SBR. So, there is NO advantage in getting one vice building a .300 BLK pistol with a folding brace, it is either a pistol or will be classified as an SBR.
The .30 carbine is the best man stopper of the bunch that you have listed. If a 110 grain bullet at 1910 FPS sounds familiar, it's because that is very close to the .300 blk from an 8 inch barrel. Problem is, you're talking about an 18" barrel.
I think your best choice is probably the Kel-tec, it does everything you want, ammo is usually available and reasonably cheap, but you MUST buy carefully, as not all .22 WMR is created equally.