What came to mind is a book I read long ago "Use Enough Gun" by Robert Ruark.I talks about using a Swift in Africa with some regret.
I don't want to get too far into the debate about whether the Swift is a hog gun.With the right bullets and good shot placement,knowledge of anatomy,etc,sure,a 17 Mach 4 is probably a crackerjack Cape Buffalo rifle....for somebody besides me.
As you already figured out(good for you!) put the Swift in the safe and select another one of your fine rifles.
I use a .257 AI with 115 gr Ballistic tips on antelope,deer,sometimes varmints.With the scope on it it weighs 7 lbs.Its a nice rifle,and I have no doubt I could be successful on elk with it,but I do not carry it elk hunting,simple because I have better choices.
IMO,our responsibility is to deliver a quick,merciful kill.
I think most of us would agree sighting in your rifle is one element of that responsibility.Developing a degree of marksmanship and limiting the range of your shots so you can confidently hit vitals is another element.Equal in importance with these is selecting a cartridge/load/bullet that will dependably get the job done.
OP,I give you credit for recognizing what did not work,and changing.I do not intend to slam you.You are OK.I have learned some things the hard way,myself.
But blowing shallow craters in big game with varmint bullets ,or shattering a forleg by shooting too far,or a gut shot cuz gee,the wind does move the bullet at 400 yds,etc,are all pretty much the same.We can make better choices.