The only real risk is that the metal in the breach is fatigued and it could fail under pressure. Fairly unlikely but possible.

Muzzle loader from that period are very simple, hammer ignites fulminated mercury in the cap... Fire goes through a small hole into the breach and ignites the powder. If the hole is clogged it won't ignite the powder which leaves you with a loaded round and no way to unload it. A cleaning rod with a swab on the end will force air out if it's not clogged. If it's clogged it will be very hard to push the rod into the barrel.

I'd have it checked by a gunsmith. Key is looking for putting or signs of rust or corrosion inside the barrel.

To fire it you'll need percussion caps and powder. Modern smokeless powder is too powerful for most muzzleloaders. You'll need either black powder which is harder to find or pyrodex which is what most muzzle loader hunters use now.

I don't consider it a bad idea to shoot it. Just have it checked out first and be sure to use the right supplies.