1 agree - Section 7(2) of the firearms act 1988
2) No , Section 7(2) of the firearms act 1988
This basically means anything which becomes a S1 firearm, remains a S1 firearm, so in essence once a moderator has been used on a firearm, it is S1 (not actually proved in case law yet as I understand for mods)
So if my head was on the block, I would argue 7(2) of the amendment does not apply to mods, but common sense would be to avoid the issue by assuming it does, and keeping well clear of the issue!
I agree, a mod is just a bit of fancy tube, until it becomes S1, so I agree use a smallbore mod on an air rifle, and it remains a bit of fancy tube, use it as a handy roller etc. etc - not S1
However once used on S1 it becomes S1, which of course can be determined by the residue in the mod so I believe there would be a problem with these.
Again as the above, once used it is S1 therefore must be itemised on your FAC (except for the air one which remains a bit of fancy tube

), quite simply you could have 4 slots each having "Moderator, no unique number" described (although some police farces will state "One 0.270 moderator for use on x) above" "One 0.308 moderator for use on x+1) above" "One 0.243 moderator for use on x+2) above"....... - and you have a number of identical mods!!

)
Julie