I did the RC Bearing trigger mod today the difference is I left the trigger return spring in the trigger group. I tried using the 5x9x3mm and leaving the trigger return spring in the gun. The problem was the bearing was too big in diameter. I had also purchased a bearing size 5x8x2.5mm I used it instead.Problem solved everything fit perfect the trigger return spring works.I also installed a longer trigger adjustment screw size M3 x 10mm instead of the 5mm. By doing this I can adjust the trigger with a heavier or lighter pull. I have it adjusted at 2.5 lbs which is perfect for me because my other guns have a 2.5 to 3 lbs pull.Its really a good trigger and its safer because I left the trigger return spring in it.I can lighten it to a hair trigger if I want to by adjusting the TRS. There was no need to leave the spring out of the gun because it is safety feature and doesn't affect the trigger pull much.
i left spring in too with 5x8x2.5mm and took screw out for now but will retry with screw to fine adjust but havent tested pull with scale.