Depends on the law where YOU live. In most places, any age, with the permission of, and in the presence of, your parent or a designated adult.
how old is my new England firearms 410 shotgun ser# NR-378884
You need to find a lawyer who is familiar with firearms law.
When you demonstrate the maturity and knowledge needed to use a weapon. This will include the basics of firearms safety and respect for yourself and others.
Criminal use of firearms
No, they do not use firearms. They are civilian organisation, and are not authorised to carry firearms. If firearms are ever required in an operation, the local police's armed response unit is contacted.
At least 5 years old
Most ranges do not provide firearms. There are some that RENT firearms for use on that range.
The use of Firearms
I think 18.
21
You have to be 21 to get a Federal Firearms License in ANY US state, territory, or protectorate.
The Police Dept can usually handle the disposal of old firearms.