My old Spikes Tactical had the same ciener bolt group as yours Jim, minus the chamber insert.

Mine was the early type and required considerable running in, to be honest, reliably wise couldn't hold a candle to my L1A1 .22 kit, even keeping it clean and lubricated. But a mate has a relatively new CMMG M4 build, it's reliable and reasonably accurate, build design appears to be slightly different from what I can remember of the original base design.

I do miss the familer AR ease of handling, when I put a few rounds though a borrowed rifle, I am reminded how the controls just fall instictivly to hand, Eugene Stoner was rather good at egronomics!