What was stated in parliament does not serve to negate the ambiguity in the proposed wording.
The blandishments made in parliament state the following. Setting aside the vague wording surrounding intent and how that might be asserted or defended, the speaker in the parliamentary summary below states that the critical test is whether it would be unlawful to assemble the components held.
So...if your licence states you can hold 50 cartridges, and you have a bucket of reclaimed brass...you have failed the critical test. BTW, the person who made this pronouncement is Simon Bayne, the Bill's custodian.
I am advised that there will be law-abiding shooters who may have components of ammunition that they use lawfully, for such purposes as reloading ammunition, which they are legally able to possess by virtue of their firearms certificate. The offence in clause 2 has therefore been drafted in a way that will not criminalise such lawful activities. It requires first that the person committing the new offence has any of the components in their possession; secondly, that the person has the intent of manufacturing ammunition; and thirdly and critically, that the person would have no lawful basis for having the ammunition once it was assembled and complete. In that way, the clause ensures that those who are able to hold ammunition by virtue of a firearm certificate issued under section 1 of the Firearms Act 1968, or who are registered firearms dealers under the Act and permitted to possess or manufacture such ammunition, will not be caught by the new offence when going about their lawful activities.