I just put together a 1911 frame, and made it so it could have a .40ACP slide which I had a gunsmith build for me. I installed a low power mainspring. My question is: HOW MANY POUNDS OF FORCE SHOULD THE RECOIL SPRING BE WITH A LOW POWER MAINSPRING? At the range, the slide would get stuck and cycle (when it did) slowly -w/ a 20 pound spring.