Yes, it should.
The GG&G Mossberg 590 Shockwave Flashlight Mount is not compatible with the 20 gauge 590 Shockwave.
The GG&G Mossberg 590 Shockwave Flashlight Mount will not be compatible with a 590 that utilizes a bayonet mount.
The manufacturer states this will work with most tactical flashlights.
This is meant to work with Shockwave models only. For non Shockwave 590 models you will want this version here: https://www.opticsplanet.com/gg-g-mossberg-590-sling-and-flashlight-combo-mount-12ga.html
Unfortunately this is for 12 Ga only.
Here is a link to the model designed for a non Shockwave 590:
https://www.opticsplanet.com/gg-g-mossberg-590-sling-and-flashlight-combo-mount-12ga.html
Unfortunately, we do not carry that product available for a 20 gauge at this time. We frequently look to add more brands and product lines to sites and we may offer this product in the future.
No, this mount will not work as it is specifically for 12 gauge Mossberg 590 Shockwave. Here is a link to a model that will work, and any flashlight with a picatinny mount will work:
https://www.opticsplanet.com/gg-g-mossberg-500-sling-and-flashlight-combo-mount-12ga.html