The skeletal setup is actually pretty simple. I can walk people through that. I guess the question is blender or maya? I could do a template skeleton but it would most likely look like the skeleton for the Magazine Firearm version of the pistol. Most of the stuff you see in the skeleton in UE4 are sockets which are needed to attach the various parts. The gun body only really needs a single bone unless you want to have parts move via animation like the trigger, or selector switches.
Bolt action firearms are coming in 1.1 and will be Magazine Firearms. In fact in 1.1 you will be getting a bolt action sniper rifle and an MP5 (Which also has a rotating charging handle).