Re the old ammo,the parts are a different matter.
The barrels are considered 'live' until they have been deactivated, same for any pressure bearing parts.
You can argue deactivated by any other means.
But in this rabid anti gun culture....
Agreed Jim, unfortunately, here in the UK, you really need to dot the I's and cross the T's with these things ... Make sure all the legal requirements are rigidly applied.
The gutter press (all of them from what I can see) would have a field day otherwise.
"Machine gun parts dug up by gun nuts shock"
Or a rabid variation of the above, perhaps including the word assault, the usual dreadful pathetically poor journalism the UK excells at these days...