Purchased a MK11 barrel as my John Inglis MK1M has a MK11 barrel fitted, asked for a Canadianicon one, 'JI' marked and got one!
Very similar to the one fitted to gun.
Don't know how it compares to one of the early Deac barrels, not much left of the lugs, and no movement of the gas port...…...at least on mine. still pleased though!