I am guilty of being overgunned up until this point. I found that everything I hit with my .300WM went straight on through and just left a tiny little would channel. Using too hard a bullet was a problem, too. It wasn't that I was overcompensating, but lacking my own experiences I was following the social norms of what I heard to be adequate, and to use a "premium" bullet always. Then I learned that I was shooting a tiny laser beam through the animal, with the equivalent of a .30-06 coming out of the other side of it into whatever is behind. Quite inefficient. I even had to find out what kind of tracking skills I have on one deer that I shot through the top of the lungs. Combined with seeing the same wound on most of the moose shot by overgunned clients at the lodges I worked for, I realized there was something to this. Especially considering the implications of moose hunting alone with the difficult places that the animal can end up, I was motivated to find a better way. I came to the realization that matching the correct bullet construction to the correct velocity for the correct range for what I want to do is much more important than simply having a big cartridge. I feel that something more efficient and softer shooting will help me to increase practice time, and increase my confidence in my abilities with the rifle.
I was just as guilty with shotguns, too, shooting 3" 12-gauge loads from an 870 clone with an ill-fitting stock. Was that ever brutal. I fixed this problem by getting more efficient with a 20-gauge of proper fit with lighter tungsten-shot loads. Every bit as effective, and it lets me do my part much better which is what really matters. I shoot a lot more now, and my skills are going to higher levels than I aspired to before.
Now I'm working on finding a more appropriate rifle. Last year, I used a Win 94 .30-30. I liked much about it, but there were a couple of things I didn't like either. Now, I'm taking everything I learned from that and putting it into a short, light, handy, all-around bolt gun. So far, my caliber choices are narrowed down to 6.5x55, 7x57, .260, or 7mm-08. With this and all of the right ergonomics (and a lot of practice), I'm confident that I can excel with such a thing.