Yes, the Anderson Manufacturing Mil Spec Buffer-Kit will fit your Stag Arms AR10. You will most likely have to tune the recoil system by using different weight buffers.
This Anderson Manufacturing Mil Spec Buffer-Kit includes a carbine buffer (3 oz). An AR15 platform rifle/pistol chambered in 7.62x39 would need an H3 buffer (5.0 - 5.4 oz) to function the best it can. I would recommend the Aero Precision AR15/M4 Carbine Buffer Kit that comes with an H3 buffer. You can find it using the following link:
https://www.opticsplanet.com/aero-precision-ar15-m4-carbine-buffer-kit-no-stock.html?_iv_included-accessories=h3-buffer
Please email us at techsales@opticsplanet.com for further assistance.
No, it does not.