Ballistics is one branch
The study of firearms and ammunition is called ballistics.
Engineering, art,
Metallurgy would be one form.
No study I am aware of that has that data.
Besides firearms, they study law, metals, machining, use of laboratory equipment, math, geometry, physics, chemistry, English (they write reports) and use of computers.
GAGO
The study of ballistics, especially its application to firearms, was developed by military scientists and engineers over centuries. However, the modern scientific principles of ballistics were formalized and studied extensively by Sir Isaac Newton in the 17th century.
Write the name of the scientific study of food and drink (especially in humans)? Write the name of the scientific study of food and drink (especially in humans)?
apiology the scientific study of bees, especially honeybees.
study
There are a lot of studies that are significant with regard to modern technology. One major study is the impact of advanced technology on society.
There ARE no websites that teach "EVERYTHING" about firearms- I have been a student of firearms for over 50 years, and I am still learning. Firearms are an incredibly broad topic- I would suggest you narrow down your interests a lot, and find some specific aspect of firearms you would like to study. That might be the history of firearms, rifle target shooting, hunting, skeet shooting, etc.