Ernest A.
Earlier I submitted comments about your Non-Slip AR Pistol Rubber Tube Cover Slip Over. I didn't include a photo. These are two photos of my AR-9. One is a full view. I've taken it to the range and was satisfied with its performance.
The second photo is a closeup showing the distance (3.5") between the charging handle and the mounting ring on the Non-Slip AR Pistol Rubber Tube Cover Slip Over. The buffer tube is a Carbine Length Anderson Manufacturing buffer tube. This AR-9 also has a Law Tactical Folding stock mechanism.
In this combination the charging handle can be brought back far enough to charge the weapon. If the Law Tactical Folding Stock mechanism is removed. There isn't enough room to charge the gun.
The locking ring on the grip is too tall. This also holds true if the Non-Slip AR Pistol Rubber Tube Cover Slip Over is placed on any short buffer tube like the Strike Industries Short Pistol Buffer or Maxim Defense CQB.
I suggest your engineers rework the retention ring and handle to allow the charging handle to pass over the Cover. I have to tell you, people I've shown my AR-9 setup like the Non-Slip AR Pistol Rubber Tube Cover Slip Over. You have a great idea. It just needs tweaking.