if you took off the recoil spring and it went on without it, then thats your culprit.

probably has some plastic slag on it or the plastic part is being a bear.

lay your slide on its sights.

looking straight down at it, make sure the barrel feed ramp is eyeball centered with the edges of the slide.

also make sure your recoil spring assembly is centered with the barrel.

slide on your frame and with one continuous motion, see if it goes full to the rear.

good luck