This Radian Weapons Afterburner Gen4 + Ramjet Combo is designed for Gen 4 Glocks, You would need the Gen 3 model as the MR920 is a Gen 3 clone. The Gen 3 Afterburner can be found by using the link below:
https://www.opticsplanet.com/radian-weapons-afterburner-gen3-ramjet-combo.html
Gen 4. So this Radian Weapons Afterburner Gen4 + Ramjet Combo will be compatible with your XR920.
Radian Weapons recommends tightening the set screw to 15 in/lbs.
This Radian Weapons Afterburner is compatible with Gen 4 Glock 19's. The Gen 3 and 5 specific combos can be found by using the links below:
Gen 3-
https://www.opticsplanet.com/radian-weapons-afterburner-gen3-ramjet-combo.html
Gen 5-
https://www.opticsplanet.com/radian-weapons-afterburner-gen5-ramjet-combo.html
The torque spec for the set screw/locking nut is 15in. pounds.
No, the Radian Weapons Afterburner Gen4 + Ramjet Combo is not compatible with the Glock 23.
The Radian Weapons Afterburner Gen4 + Ramjet Combo will work with a Shadow Systems MR920.
No. As of now, the Afterburner has only been made and specifically designed for Gen 3-5 Glock 19 model pistols.