Building an Retro Mag

[FeWolf]

OK I need alittle help, I want to build a retro mag, will I need both the Valve/bolt and the trigger frame to get the retro firing forward and backwardss?
I have a Lvl X know on a ule frame. :headbang:

[SpecialBlend2786]

you'll need an RT style valve (Xvalve, emag valve, RT valve) to get reactivity. The ULT trigger will lessen the reactivity though