I've had a RRA NM A4 for 4 years and put countless rounds thru it. Then one day I let the bolt fly and it fired off 2 rounds. I went no further.
Called RRA and with zero fuss they gave me a return # and free UPS shipping. I shipped it to them and in about a week I had it back in fine working order.
Since, I've bought a new RRA carbing complete and a stipped lower for a Spike's dedicated .22LR upper.
If RRA made a dedicated .22 rimfire upper I would get one.