i WOULD NEVER BET MY LIFE ON AN UNPROVEN PLASTIC RIFLE. If you have 4 SHTF guns buy food and meds you'll need them
What would you consider proven?
The FS2000 is a semi-auto version the select fire F2000, which has been adopted by multiple armies.
I'd suspect the parts commonality between the FS2000 and F2000 is a close as that between the average AR-15 and M16/M4.
H