The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Is there any reason why I shouldn't store muzzle loading pistols or shotguns with the barrel off?

The cabinet is in the house and not vulnerable to heat, cold or damp.

I find I can fit them in better if I separate woodwork and barrel. The shotgun is too long to fit in a cabinet assembled anyway.

I'd appreciate it if anyone could share their thoughts on this.

No real reason why not.
Some shotgun cabinets are designed so you have to store them 'broken' and then the cabinet doesn't take up too much space.