As I recall, tapered barrels with the 'Snakeskin' finish as above were produced on a vertical GFM cold swaging machine which was capable of hammering a tapered blank. These barrels then only required machining at the muzzle and breech ends.
Later barrels were produced on a horizontal 'Fritz Werner' machine which could only hammer a parallel blank. The barrels therefore had to be turned full length and have a normal machined finish, plus usually a stight step in the centre where they were supported by a lathe 'steady'. Some may also have polygonal 'Chordal' rifling rather than the traditional Enfield form but I do not have the dates.
All surplus machinery from RSAF was sold on-site by auctioneers Henry Butcher Ltd on the 16th and 17th November 1988. This was after shipping what was needed to the new Nottingham Small Arms Factory, and selling some items to RSAF employees who had bid for them. I believe that the GFM machine was bought by Geoff Lonsdale, a former shop manager of the barrel mill. The FW probably went to Nottingham and was disposed of when that factory was closed by BAE in 2002.
Properly looked after the barrels should, I believe, have an accurate life of over 4,000 rounds but others may have more detailed figures. As has been mentioned by others, used barrels should be available from scrapped first generation target rifles: try Fultons or English Armourie.