I have contacted S&W in the past about this. The slide lock can be used to release the slide without any issues.
By the way, if the slide is locked back, slam the loaded mag in and most of the time the side will automatically unlock and chamber the first round.
And yes, slam the mag in, you are not going to damage the gun.
Also if you have a loaded mag in the gun and the slide is locked back, grab the slide and yank it back. The slide lock will automatically unlock. You will not have to pull it down at the same time. NEVER walk the slide forward, yank and release. Walking the slide could cause to not properly chamber a round and/or go into battery.