Jakebomb97

So I have a used l96, most likely one of the well models I’m not quite sure, I bought it used many moons ago, recently installed a lot of new parts, I have a novritsch cylinder, trigger box and hop up rubber the the thing just doesn’t seem to be cocking back when the bolt is pulled, I do have a bell piston and spring guide, but I’m not too sure on the strength of the spring, can one of you find gents point me in the right direction? Much appreciated