i just got a No.4 Mk1/2 whic was listed as FTR in 1955. originally a 1944 No.4 mk1, it had been rebarrelled with a F55 barrel and it had also been re serialed into the Fazackerley No.4 mk 2 serial range. This was A 12XX. Was this a common practice? I've never seen this before.