To be perfectly honest, I wasn't aware that Sterling manufactured a 223/5.56 rifle. Although as everyone knows they built and designed the brilliant little Sterling SMG as well as manufacturing the De Lisle silenced 45ACP carbine, built on the Lee Enfield action.
A chap in the USA is producing a very close copy of the Sterling, from the photographs he sent to me, its a really nice weapon complete in a nicely made wooden box, Sterling/Lee Enfield Number 5 bayonet, 3 magazines and quite good copies of the original MOD users manual.