I have been given serial numbers without the prefix's .... that in the end became useless to me when trying to sort out if its Enfield or BSA and the reason I'm starting over with the search for confirmed details. But I think a lot of that was because the numbers people gave me came from Breech Blocks and Carriers. I think especially with BSA rifles you could quite easily loose the prefix to the serial number (and the serial numbers) as they seem to be hand engraved, they certainly don't seem to of been done with a pantograph or engraving machine. On the other hand the ones from Enfield you could lose a small child in the engravings.