To do a "human" kill on goats the 22 rim fire is too small.
If money is the issue among the best rifles that you can get for less than $ 600 is the Carl Gustav 6.565.
King gustav commisoned this rifle as a high presion rifle up to 800 mts.
It is very gently on the shoulder and it is a pleassure to use.
If you like to have something more modern a remingto rifle with a 700 action would be the way to go.
I like flat trajectory and easy on my shoulder so the 22.250 is mi fav.
The 700 action is very good if you would like to have a custom made 6mmBR which is among the best for long trajectory shooting.
You can build two separate safes for your vehicle, one to carry the rifle and a small very strong safe for the bolt and the amo.
Please do not use a small rifle for medium game ;)

