AFAIK there is no requirement to record purchase of primers on your ticket. There is a requirement to verify that you are allowed to purchase primers. According to the current HO guidance:
5.16 The Violent Crime Reduction Act 2006 introduced controls on the purchase and sale of cap-type primers designed for use in metallic ammunition for a firearm, including empty cartridge cases incorporating such a primer. Section 35 of the 2006 Act makes it an offence to sell these items unless the purchaser:
a) is a registered dealer;
b) sells by way of any trade or business either primers or empty cartridge cases incorporating primers;
c) produces a certificate (i.e. the original, not a photocopy) authorising them to possess a firearm of a relevant kind (i.e. a firearm other than a shotgun, an air weapon or a firearm chambered for rim-fire ammunition) or ammunition for such a firearm;
d) is a duly authorised Crown servant;
e) shows that they are entitled in law to possess a firearm or ammunition of a relevant kind without a certificate;
f) produces a certificate (the original, not a photocopy) authorising another person to possess such a firearm, or such ammunition, together with that other person’s authority to purchase primers on their behalf; or
g) shows that they are authorised by regulations to purchase primers. To date no such regulations have been made.
Section 35 also makes it an offence to buy, or attempt to buy, primers unless the purchaser meets the same criteria.
The definitions used in section 35 mean that the offences do not apply to the purchase or sale of blank ammunition, shotgun primers or to percussion caps for muzzle-loading firearms.
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