Good question Pat and one that everyone should take note of. In fact, the term 'unissued' is one that I sit a chuckle at whenever I see it. The still-in-wrap rifles are the exception in my opinion.
Rifles tend to be delivered from Ordnance to the unit is green plastic sealed bags with the usual labels tied of threadad through them. When you open the bage, the rifles are bount at the ends and extremes, like foresight blocks, backsights over the cocking handles - you know the sort of thing - with cream coloured heavily waxed 'amalgamating tape' that's difficult to pick apart when it's amagamated.
Once at the unit, they'd be unwrapped, cleaned down by the Arms storemen, serial numbers checked and entered on the quartermasters master ledgers. They'd be allocated to a person and that would be 'his' rifle while he was at the unit. It'd be used in the everyday running of the unit. Ranges, shooting exercises, parades etc etc and it'd be his.
When stuff goes back to the main Ordnance stores it's usually for just a few reasons, such as the unit is going off to Germanylet's say and will be re-equipped there or it has been returned because it's worn out, beyond the scope of Field repair. For the latter reason, once it gets to Ordnance, it is examined and sent either for Base workshop repair at the Ordnance depot workshop, disposal or scrap.
Those disposed of that are wrapped in their green bags aren't new or unissued at all............. they're rebuilt to sit in the Ordnance Depot. Ordnance depot's only KEEPS, RETAINS and ISSUES PERFECT stores.
When large stocks of ex AustralianBrens and Vickers guns were disposed of in the UK
for the deactivated market, many new owners were telling all and sundry that they were new and unissued, just because they looked new and were covered in grease! What a load of pure horse sh......, er....., manure. They'd been withdrawn from service, gone through the Ordnance refurbishment system and put back in store in A1 condition ready for re-issue.
Nope.............. I share your coments to a tee Patrick. We don't buy this stuff to keep in stores forever. Ordnance stores full of unused stores is just an expensive way of storeing fresh air