Decade Corp M4 Straight Pull in .223 Remington.
AR-15 Style which takes AR-15 parts.
Has a Magazine and Open sights.
Rifle built on standard mil-spec upper and lower with a standard T-handle rear charger (extended catch). Bolt and barrel extension lugs are fine as is the bore.
I do have a scope I could sell with it which is a BUSHNELL AR223 4.5-18X40 with Rings will be £200.