I put the slide on before installing the barrel. I also remove the barrel first, when taking it down.
It fought me just a tad when I was putting the barrel back in. I just took it out and tried again.
Movie I made a couple of years back, showing how to disassemble and reassemble. Click on it.
Meddle not in the affairs of dragons, for thou art crunchy, and taste good with catsup - George of Lod, Year of Our Lord 297
I always take precautions.
Beware the Evil Bullet Fairies.