Hello everyone, I have a question about the assault rifle M4 loaded. I saw they reloaded it on Youtube, they reloaded in two ways. One, they removed the mags, and then pulled slide back and release slide back to chamber round. Two. they removed the mags normally, but after that they didn't pull slide back, they hitted a button or something like that, above and on the left of the trigger. Somebody can explain to me the second ways? Thanks!