James, According to sig no it's proprietary and not interchangeable with AR stocks. The stock attaches using a 1913/picatinny rail, So you can easily add a buffer tube to attach any AR stock you want. Here's a link to a picatinny buffer tube that would work if interested. Hope this helps, link here............. budsgunshop.com/product_info.php/products_id/127158/midwest+industries+mistap+stock+tube+adaptor+black+hardcoat+anodized+aluminum+ar-platform

As mentioned below, it is Proprietary and will not work unless you add the piccatinny Buffer tube.

James, it is proprietary Sir and not compatible with standard AR buttstocks. The attachment is via a 1913 Picatinny adapter/rail. You would be able to use any Picatinny based stock to attach. Example : https://a3tactical.com/modular-stocks-picatinny-1913/

As mentioned below, it is Proprietary and will not work unless you add the piccatinny Buffer tube.