Howdy
I've built 2 guns on Essex chopped frames. The only difference is the essex has a longer grip, 3/32inch, and a longer dust cover, 1/8inch. Both of these I cut down to Detonics size. Also the CM frame is slightly heavier. The essex frames are good, I've had no problems. I've built 15 guns on them total. The grip plug does normall require fitting. I've found it easier to cut and make my own out of a full size grip safety.
Hope this helps.
L8r
Conley
USMC 87-93