Learning lessons today. Spent some time on the practice project. All in 
all it turned out well. But not as good as it needs to be. I 
counter-sunk the number #30 holes in the aluminium angle. They were 
perfect if I used the 426AD4-4 rivets, but when I put the 0.040 dimpled 
skin over top the angle... Skin does not sit flush on the angle because 
the angle countersink was not deep enough. Makes perfect sense now that I
 think about it, but I realized it after I riveted. I also played with 
the air settings on the gun and found that lower settings work so much 
better that the higher settings I was using. I also discovered why the 
flush rivets do not sit quite so flush with the skin. My swivel flush 
set has a rubber ring around it which sits proud of the skin. Unless I 
press really hard with the gun, there is a possibility that the rivet is
 driven with its head slightly proud of the skin. I also noticed that I 
scratched the head of my flush set so now each flush rivet is being 
marred. After reading up on the forums, I see that you can polish the 
flush rivet set (one the rubber is removed). Did that and it turned out 
very nice!
