Like all terms in the British gun trade they have been used and misused over the years so that the original meaning is not always exactly correct .
An example is that of "tail pipe" .Originally this was the metal escutcheon at the front end of the stock on a muzzle loading gun into which the ram rod was entered . The term has continued in use to mean virtually any forend tip .
Furniture is a general term that encompasses all the parts that are not directly part of the working mechanism of the gun ,BUT , the trigger guard ,trigger plate and triggers are also commonly called "the furniture" , these were usualy made up by "furniture filers" who also filed up other small parts such as tail pipes and heel plates .
I assume the term would have been coined in the early days of gun making where the "furniture " would have been something that fastened onto the wood of a muzzle loading gun , probably taken from the furniture's that would have been fitted to doors etc .
The trade was never one for not reusing a perfectly good existing term .
