Align object to bone without constraints.

I’m looking for a sane way to align object to a bone. To be more specific - a child object parented to a bone, so child location/rotation matches those of a bone.

Situation:
You have an armature, and you have an Object parented to one of armature’s bones.

Goal:
Modify object transform in such way that its local XYZ axes and world position perfectly match those of a bone.

Restrictions:
This shouldn’t be done with constraints. Meaning object position shouldn’t be in the right place because constraint is enabled.

Practical example:
You have a skeleton with weapon bone, and you have a modeled gun at origin. You need to attach the gun to weapon bone as a child so it snaps properly in the right place.

NORMALLY, in most software this is done by zeroing local transofmraion of a child object. When local transform is set to identity, the child object will perfectly align to a parent. However I don’t exactly see any local transofrmations exposed in blender GUI anywhere, and there’s nothing on the web regarding that. This really should be a one-click or one-hotkey operation.

Ideas? I’m using blender 2.78c on windows 7 64bit.

Either I’m missing something incredibly obvious, or there’s a huge oversight.