Lead Moderator European Armoury
Join Date: Dec 2004
Not a cannon breech but one of these multiuse 'noise makers'; in this case to go bang during religious festivities, judging by the cross. No ammunition needed, just gunpowder and a wad. It is used upright.
I wouldn't think that it is spiked to avoid its functionality but to have a new life ... like for melting lead, as per your words.
The one (among several) that i have with a cross was bought in a French site.
They can be very old. Difficult to precise; maybe someone with more knowledge.