I used it once. Comes with a BCG and 3x 25 round magazines
Price for the kit is $175
I can meet in NoVA or reasonable distance from NoVA. You can contact me on here or text me at 571-310-2979
From the CMMG's website
https://cmmg.com/22lr-ar-conversion-kit-mk57-w-3-magazines-25rd22LR AR Conversion Kit, Mk57, w/3 Magazines, 25rd
**THIS KIT IS FOR CONVERTING 5.7X28MM TO 22LR ON OUR 5.7 CONVERSION UPPERS ONLY AND WILL NOT WORK WITH .223/5.56 CHAMBERED RIFLES OR OUR MK57 LOWER**
Easily convert your CMMG 5.7x28mm Upper Receiver Group into a .22LR in seconds! The new Mk57 .22LR Conversion Kit is simple to use. Just remove the existing CMMG bolt carrier group from your 5.7Χ28 upper and replace it with the drop-in conversion. Pair the upper with any Mil-Spec AR15/Mk4 lower receiver and then use the included magazine to safely shoot .22LR. Its a great way to get in more trigger time while saving money on ammo. This conversion kit is designed for use with all CMMG Mk57 5.7x28mm upper receiver groups and bolt/barrel combinations when paired with an AR15 Lower.
Kit Includes
-5.7Χ28 to 22lr conversion
-Three 25rd Magazines
Stainless Steel Construction
Compatible with all CMMG Mk57 Uppers
Magazine Fits in Mil-Spec AR15/Mk4 lowers
Simple Installation No Tools Required
Not compatible with Mk57 Lower Groups or 5.56/.223 uppers.