This fit perfectly on my late 80's mossberg 500 - VISM Mossberg 500/590 M-LOK Handguard

After watching so many reviews on the magpul not fitting certain older model 500's I was a bit concerned this wasn't going to fit. This took a bit of coaxing but it fit like a glove. I didn't have to measure the slide or anything. I was able to get the retaining nut off with pliers( didn't buy the specific wrench) and I tightened it back on with the same wrench then a screw driver on the slot of one side. Worked like a charm. I have the matching magpul stock and they color match . looks great!