spring back (of an object)

What would be the normal Greek for 'spring back' in the context of something you try to bend into position but when you try it always springs back/jumps/bounces/recoils back to a place. The natural elasticity of an object makes that object return quickly into position. It is the same when you pull two shrubs aside to find something you have lost in them but each time the shrubs spring back to the vertical. Examples:-
-The lid sprang back to a closed position.
-when I bent that bit of plastic back, the blasted thing jumped back & cut my finger.
The word I'm looking for is typified in the story of the sad end of Milo of Croton. The Greek word used in this account is πετάχτηκαν:-
Ο Μίλων έζησε ένδοξα, αλλά το τέλος του ήταν τραγικό. Σε μία βόλτα του στο δάσος είδε έναν κορμό δέντρου, που μόλις είχε κοπεί, με σφήνες μπηγμένες μέσα για να τον ανοίξουν. Αποφάσισε να χρησιμοποιήσει τα χέρια του για να τον ανοίξει, αλλά, καθώς προσπαθούσε, οι σφήνες πετάχτηκαν και τα χέρια του παγιδεύτηκαν μέσα στον κορμό. Δεν κατάφερε να απελευθερωθεί και, όταν ήρθε η νύχτα, τον σκότωσαν τα αγρίμια.

Is there a better word or does πετιέμαι convey the meaning of the elasticity of an object which causes it to recoil quickly.:scared::angry:

I would say that generally the best option is αναπηδώ, but it's not suitable in the excerpt you're quoting. On the one hand, you wouldn't use spring back to describe what the wedges did, so πετάχτηκαν isn't the word you're looking to replace. However, you'd use spring back to describe the log slamming shut; so I would suggest using (ξανά)(έ)κλεισε απότομα here.
In other instances, spring back could be translated with επανέρχομαι or (ξανα)ισιώνω.

Thanks, dharvatis. I always fight shy (somewhat irrationally) of πηδάω & compounds because of its sexual connotation. Daeman commented on the difference between αναπηδήξαν & αναπήδησαν, seeming to argue that, in his opinion, the -ξ- form is colloquial & has such sexual connotations: see 'Outside the Underground Station' English-Greek thread, p. 1, penultimate note.