Lorne,
I have trapped/shot hundreds of beaver a few years back when fur was paying my bills.I have shot them with22 long rifle,22 mag,.222,22hornet,downloaded22-250,220 swift.7mm mag(down loaded again) and in the last years 17 remington. The best caliber without a doubt was a 17 rem,now with the 17 hmr out is is possibly the best cartidge available for this task.Over the last 4 years since I have obtained the little 17,alot of beaver have been harvested with it.I do not believe that there has been a exit with a headshot on any beaver.A ear shot is absolutly devastating.I will however say that a few more dead beaver will sink,not as many as with a 22 mag but you will loose a few .Overall use it will confidence,it is a winner
bulletsmith