FN 57

You’re concerned about bullet weight... If you might happen to reload, any standard .224 bullet can be used. But the higher weights will slow greatly with the limited powder capacity.

Now you have me wondering about the twist rate? And does anybody make aftermarket barrels with a 1 in 9” or 8” twist rate?

Wyman

I have one.
It makes for an interesting range toy. I couldn't imagine using it for anything else.

It has few things going fot it light weight with high capacity plus the AP cartriges.

It's elderly or manually challenged friendly due to the easy to load mags, low recoil and light slide effort. The report is quite loud though. Very high quality and reliability. The gun I'd buy for my mother were she still alive.

The ammo can be found sometimes on sale through PSA, $15 per 50 rounds.

I use mine as a 22 mag rifle that fits on my hip. Great 100 yard varmint round. Its accurate too. I have competition guns in 9 40 and 45 and 10mm and hunting revolvers in 44 45 460 and 500. The 5.7 is as accurate as any of them with no recoil . Its also a very well built handgun. Great for beginners too although the noise is pretty loud, absolutly no recoil, good triggers on both of mine. Its a great range toy. For sd its rather low on my list. Near the bottom actually but above 22/25/ etc. I prefer 10mm then 40. As far as what caliber would be best if shtf.... that would vary by where you are. My county carries 40. City carries 45 and troopers and game wardens carry 357 sig. I carry a 40, but realistically would be dead long before I ran out of loaded mags, much less ammo in boxes. But if survival is your goal I agree 5.7 makes no sense. Other than the fact that I can store more than 3k in a 50 cal ammo can, it doesn't have much going for it.

Other than that I think it was a highly overrated failure. But that's just my opinion and I have 2. As far as bullet availability, reloading the 5.7 is a pain in the arse. I'll gladly pay my 20 bucks for 50 fn branded vmax rounds. I save my brass (the gun throws brass a mile away so plenty is lost. Also polymer coated brass blends in with grass) and have the dies but as long as ammo is available..... nope. And btw I reload for every other round mentioned. It wasn't my first choice but If you live in a free state and have the cash, go for it no one has ever fired mine without liking it. But as far as I know only one bought themselves one.

If you are looking for something that can punch body armor then look at the 7.62.25 Tokarev.

Gun is cheap and ammo is reasonable.