Dimpled the spar bottom flange and 26 inboard top flange holes, cleco'd everything in place for riveting. Trying to make sure which way the rivets go - for most the spar is the thicker material, so shop heads should be on the outside. Shop heads on the inside would be more aesthetically pleasing. Quick search of other builders blogs seems to show shop heads on the inside. That would be consistent with how I did the HS too.
Riveted the spar with various sizes called out in the plans. Was able to squeeze most but had to buck a few awkward ones, particularly near the root. Bucking gun was fine except one that the gun jumped and obliterated the rivet head. Had a very hard time drilling it out and tore up the hole a bit. Tried to save but went with another AN bolt. Just one of several in that field of rivets at the rear attach doubler. Biggest problem is that it is not easy to inspect.
5/4 update: back-ordered bearing arrived so was able to complete the aileron bracket assembly and rivet to rear spar. I used just some rubbing alcohol to remove some tape residue from the rivet heads and was very disappointed to see some of the primer come off. Will need to really consider the EkoPoxy for the fuselage priming.