I bought a tigershark from my friend earlier today. (for $10

) Its in great condition and only missing the pump handle. But I can't get it to come apart... I must be doing something wrong. I tried unscrewing the little plastic screws and that didn't work, then I noticed that if you pushed the screw it would go about halfway out but then stop. Help me...

I'm planning to sand down then hook up my phantom overcocking pump handle. Then i'm going to tap the valve through the grip and put in a 12 gram changer. Slap on a feed tube and it'll be ready to go!