I've been much annoyed with the 5.7x28. My wife owns the original FN version. I waited for the Ruger. Either way, the ammo has become prohibitively expensive. My Ruger is still NIB, unfired. There is some "glue" involved in manufacturing 5.7x28 that makes it more expensive.
I recently saw a Youtube video on a new 4.6x30 round that is in an all brass case. Cheap to manufacture. It is offered by HK
PDW ROUND COMPARISON 5.7X28MM VS 4.6X30MM
Looks pretty zippy.
I’ll stay old school, for now.
30-06, .223, 9mm, .38Spl, .44 Mag, .22Wmr and .22LR.