10/20 Magpul 223/556 Gen M3 has a rivet installed to only allow 10 rounds in the magazine. Comes with dust cover and open retail bag.
NOTE WHEN LOADING THE MAGAZINE IN THE RIFLE YOU WILL HAVE TO GIVE IT MORE OF A HIT TO FULLY SET IN THE MAG WELL. THIS IS DUE TO THE 10TH ROUND BEING TIGHT IN THE MAGAZINE. TO ALVOID THIS YOU CAN LOAD 9 ROUNDS INSTEAD OF 10 ROUNDS. OR HAVE THE BOLT FULLY BACK BEFORE LOADING.