Those Magpul risers are not designed to be used on AR-15 rifles as they will interfere with the charging handle. They are designed to be used on bolt action rifles that use AR-15 style receiver extensions.
The Strike Industries Modular Fixed Stock is designed to fit Mil-spec carbine length buffer tubes/receiver extensions or the Strike industries Advanced Receiver Extension 7-Position buffer tube. A5 receiver extensions are also compatible with this stock.
The Strike Industries Modular Fixed Stock does have a universal sling loop at the bottom of the stock that you can weave a sling through. The Magpul MS1 would be my recommendation.
https://www.opticsplanet.com/magpul-ms1-multi-mission-sling.html
Because compliance and regulation issues change frequently depending on the exact state, city and county you are in, we cannot provide an accurate answer. You would need to seek local guidance, or place an order for the stock so that our Risk Management and Compliance department can verify current compliance based on your exact location.
Strike doesn't make an adjustable cheek riser. There may be universal options that you can try, but fitment would be an experiment.
Per Strike, a standard mil-spec castle nut, buffer tube and endplate must be used for proper installation of the Strike Modular Fixed Stock. You may be able to get away with a sling loop, but the QD mount will be a definite deal breaker on fitment.
We are not aware of any ATF regulations regarding stock length, however this can be adjusted with the addition of spacers from it's base length of 12in up to it's longest length of 14.25in.
No, it is for mil-spec carbine buffer tubes.
It is for mil-spec carbine buffer tubes.
As long as your current buffer tube is a mil-spec carbine length model this will fit. It is held with a proprietary bolt set up. Strike Industries installation video can be found here:
https://youtu.be/wirlwvWjJk0