Chaded the lines are certainly blury on this topic. Take a Sharps rifle for instance.

Shiloh Sharps makes EVERYTHING in house including the barrel. It can takes years to get one after ordering. They are considered the pinnacle of Sharps rifles.

C. Sharps. Slightly less desirable than a Shiloh and they used Badger and/or GM barrels. Last i heard they can only get GM barrels now. These can also take well over a year to get after ordering

Pedersoli. They make a Sharps rifle and i can walk into many outlets and buy one off the rack.

These are just to name the most popular brands (more or less). The first 2 are certainly better made but are they customs? I think its completely safe to say the Pedersoli is a production rifle. The other two well......its a tough call even if you buy a base model with no options.