AC7PN wrote:

...
But now I have a new problem. When the thing went off the 4lb fishing
line played out for about 8 seconds. It's still connected to the
projectile but after seaching the woods for an hour I couln't find it.
The trouble is I don't know how far it went. 100ft 100yards or
100miles. The 4lb fishing line is invisalbe from more than a few feet
away.

What now?
...

Drag a rake perpendicular to the direction of the line, across the lines
path carefully watching?

Once you find the line, you got the projectile ...

Regards,
JS