ReTro mags have an upgrade called the ReTro valve, its the same technology thats used in the RT's, RT Pros, and E-mags (minus electro trigger). It has a "Reactive Trigger" which means it kicks back, e.g. you pull the trigger with 4lbs of force, it pushes back with 8lbs.
The accuracy will be the same as the old valve, and its just as reliable, but you have to use it on air only, no Co2. It just gets a lot higher ROF than a 68 valve.