Yes, the XTS AR Cheek Rest Stock is compatible with QD Sling Swivels.
This XTS AR Cheek Rest Stock is a stock and will convert any firearm with a barrel shorter than 16" to an SBR. We do carry braces for AR pistols that you can find using the following link:
https://www.opticsplanet.com/s/pistol-brace?_iv_gridSize=240
The stock does adjust. Look closely at the bottom of the front end. The release button is there
The XTS AR Cheek Rest Stock will fit any Mil-spec, carbine length buffer tube.
The XTS AR Cheek Rest Stock fits Mil-Spec carbine buffer tubes. The Springfield Saint Victor AR10 uses a Mil-Spec buffer tube so the XTS AR Cheek Rest Stock will work with that rifle.
From what information I could find the HK416D .22LR model is compatible with AR Stocks that fit Mil-Spec buffer tubes. So the XTS AR Cheek Rest Stock should work fine on an HK 416D .22LR.
Yes, the XTS AR Cheek Rest Stock will fit a Springfield Saint.
Almost but no. I would be surprised if they aren’t made in the same factory and would put money on it. They are functionally the same. However, besides being much cheaper, the XTS is better in the fact that it also has slots to thread your sling through and the 104 model also has QD sling sockets on both sides. The cheek rest will flex some in the front if you put too much pressure with your cheek but could easily be fixed by placing a piece of foam or something solid under the cheekrest or setting to account for a little flex if you press hard. Haven’t installed yet to comment on how tightly it fits without rattle but that can always be mitigated with a strip of electrical tape on the buffer tube to take up slack if it turns out to be an issue. Otherwise it seeks as good as the 9 other stocks I reviewed from Magpul, BCS, and B5. If you need a riser or plan on removing or keeping the riser collapsed, I recommend this stock and was quite surprised with the quality of a $24 stock.
XTS states this item weighs .085 lbs without the packaging.