@Bert the Turtle what's the real difference between the first and second edition?
		
 
		
	 
Mainly, it covers more species.  
From Safari Press:" Kevin “Doctari” Robertson’s best-selling book on shot placement for African game, The Perfect Shot, has now been completely revised and updated: extensive additions to the text; 300 all-new photos of the animals covered; and revised, detailed anatomical drawings. 
The Perfect Shot II also has shot-placement details for a number of species not covered in the original edition, including blesbok, bongo, black wildebeest, grysbok, nyala, reedbuck, roan, and steenbok. In all, twenty-seven African game species are now covered."
The discussion of projectiles is brought up to date.  
The addition of more species is nice but not really important from a shot placement perspective: if you know where to shoot a blue wildebeest, you can probably figure out where to shoot a black wildebeest.  The discussion of the various species is more valuable in my opinion.
Overall, if it were one or the other, the second edition is more comprehensive, but I would not say you are at any practical disadvantage if you only have the first edition.  If you like Dr. Robinson's writing as I do, then there is more to read in the second.  Probably more than anything else, I purchased the second edition because I think Dr. Robinson has made significant and valuable contributions to hunting through his books and I want to support that.