spud yeti wrote:What is the range of a well-built small(ish) coilgun?
Depends on how well made.
Google something like "disposable camera spy coil gun BB".
There is a site out there that will sell you plans to convert a disposable camera into a "spy" coil gun that fires BBs. The barrel is hidden in the camera and the muzzle is where the camera's lens was. They have a video showing the "camera" shooting a BB and knocking over a Scrotch tape dispenser at a range of 2 or 3 feet.