I've seen many recommendations on pinning the firewall. When I first heard about it I had no idea what was involved, and it wasn't until I got a giant scale airplane that I saw the light. I knocked this job off in about fifteen minutes (including time for photos).

Step 1 - Mark the locations for the pins

Using a ruler and eyeballing from diagonal corners of adjacent tenons, I made an X between each.



Next, I used an awl to mark the points for drilling.