I've got what i think is a brunswick rifle with it's bayonet.
My father gave me this as a restoration project (wallhanger), but it's got the wrong barrel with it.
The rifle is as far as i can tell a brunswick made by wilkinson, but the barrel seems to be from a percussion shotgun.
I've no idea which gun the barrel is from but it's a smooth bore, and the wall thickness tapers towards the muzzle and seems way too thin for a ball firing gun.
This barrel is sat in the stock so the gun could be displayed on a wall mount,
It's not fixed at all and it does not quite fit into the stock (the stock would need to be cut to fit the barrel properly).

I would like to change the barrel for a more suitable one and would like to be able to shoot it in the future but I'm unsure of the legal requirements.
I've even been thinking it would be a lovely place to start a ball reservoir airgun project, but the legal issues are the same i presume because it would need to be well over the airgun limit.

The problem is this,
If i change the barrel would it then be classed as a firearm rather than a curio, If so how do you go about aplying for an fac for a gun that doesn't legally exist untill you build it?.

Would i need an fac to purchase a barrel? Is the barrel considered the part which makes it a weapon?

Lots of questions I know but any advice would me much appreciated.