Indians For Guns

i remember someone telling me that magazines are considered almost like a fully functioning firearm according to the arms act.
suppose i want to build a higher capacity magazine for a licensed 30-06 rifle or an extended tube mag for a pump action shotgun, do i need a special license for it or is it illegal altogether???

thank you for your time gentlemen(and women),
regards,
technical

IMHO, the manufacture of firearm parts which includes magazines for sale to others definitely requires a license. However since there is no restriction on magazine capacity (only your ammo limit will apply).

An already licensed dealer who has the correct permits to alter, convert or modify firearms can do what your asking.

The normal servicing & routine maintenance or repairs can be done by you. Even fitting of accessories such as sight / scope rails, slings and such can be done by you.
The question really is not one of altering your firearm, but of producing firearm parts for the sake of fitment to your existing licensed firearm, this is a grey area really, because your normal license will not include a clause for manufacture of parts (even for yourself).
Now in day to day life how well this is scrutinized or enforced is a different matter altogether. It is best done by a licensed dealer/gunsmith and you are safe.
Regards,
Anand