Sadly, I
still have not finished the project.
Yes, XM15 milled my CCM frame, probably about 9 months ago.
The inside top was opened more to allow for sear movement and a notch was drilled for the twist-lock assembly (although I'm using a ULE body so it really wasn't necessary). The hole for the rear frame screw had to be opened a little to accommodate the rail bushing too.
You will not be able to use a standard rear frame screw unless you have the frame milled flat. I wanted to keep the CCM look (and avoid re-annoing a brand new frame) so I just used a stainless button screw instead.
He had modified my trigger as well, although in retrospect, I would have preferred to adjust the sear-rod length. The trigger job is kind of hokey... there's a pin installed just in front of the trigger to prevent forward travel and notch in the back of the trigger for the sear-rod to sit in.
I very briefly tested this and had some chuffing issues, but the valve was not really tuned either. I'm not sure if the trigger job is the culprit or just need to work on the valve a little.
I'm hoping to finish up the project soon, it's been sitting on my wall unfinished for months
I'm having some binding issues with my pump kit but that's a completely different story.