DAvid, Here is a set of sling swivels. $13 and free shipping.--------budsgunshop.com/catalog/product_info.php/products_id/44429/u+mike%27s+mag+cap%2fswivel+set+m500+12g
David - if it doesn't come with a sling, then it would be very easy to purchase adn install an adapter of your preferred style.
David, yes you can for th models that don\'t come with the sling swivels. gggaz.com/mossberg-shockwave-quick-detach-rear-sling-attachment.html
the Mossberg site shows it with the sling swivels installed I suggest contacting Mossberg and seeing if this is correct or if you can get the factory swivels mossberg.com/product/590-shockwave-6-shot-50659/ contact Mossberg at Tel: (203) 230-5300 | 8:00am-4:30pm Eastern Fax: (203) 230-5420 or mossberg.com/contact-us/