I never thought of the warranty, thanks RoginaJack.
I reckon I'll just end up buying the Zastava and leave it at that. It's pretty obvious that I'm going to have to buy a dedicated target rifle in order to be competitive with target shooting. The guys at the club are happy for me to continue using all of their equipment whilst I'm target shooting, so maybe I'll have to just make a start, and then save up bit by bit.
Of course, if my back stays stable, I can go looking for work again, which will make it all that little bit easier!
Thanks for all the advice guys!

Jenna