I have added a simple modification to make adjusting my breech seaters depth much easier.  It just requires a threaded hole in the body.  I am using 6-48 since the thickness is only about 1/8" at the hols location.
Here is the exploded parts diagram and the new coupler lock screw in use.  It locks the coupler in place so you can loosen the steel shaft and/or set screw to adjust seating depth.  Without the lock, the coupler has a tendency to rotate making adjustments harder.  The old instructions said to insert a small tool into the hole at the rear of the coupler to hold it in place while adjusting which sometimes requires 3 hands.  Now the 6-48 coupler lock screw can be used to lock the coupler in place during adjustments.  It needs to be removed before use.

Jack

I just invented the threaded hole!  Off to the patent office. Just think of all the royalties!

Dang!