Chamber
Chamber or barrel.
breech
breech
The caliber
A bore refers to the extremely fine or narrow tube found in a thermometer. It is called a narrow bore or a capillary.
They are called riflings
Bore water
Oversquare
Because that's what the bore measured out to.
Using calipers, the bore size of a trombone is determined by measuring the inside diameter of the inner slide at the bottom. You must remove the outer slide to do this measurement. Extreme care should be taken when handling the inner slide for this measurement.
The Severn Bore.
In Biblical times, the tree that bore the almond was called the Luz.