I don't have any problems with a 4x on small critters. I've shot pop cans out to 150 yds using a 4x on a .17 HMR and on a .22 mag. I'll admit that I can shoot better target groups with more magnification, most people can. I also can tell you that once the power goes over 10x or 12x at most, I don't shoot any better, because I start being too concerned about my shaky image. If you think about it, looking through a 4x at 25 yds is like open sights at 6 yds. Thats 18 feet. I don't have any problems seeing a squirrel, rabbit, or whatever at 18 feet, and I wear glasses to correct a bad left eye.
What you should do is get with one of your friends, and use his rifle to look at different small animals at varying distances out to 50 yds or so, and see if you like 3x, 4x, or whatever to take the kind of shots you that you want. If you like lower magnification, go with that. If you are more comfortable with a higher power like 6x, get one of those, or get a variable with a top of 7x or 9x, so you can keep the power down until you need it.
Nothing is worse than walking through the woods and then that trophy buck, rabbit, etc., jumps up right under your feet and you can't find it in your 10x setting. I've seen it happen so many times....even with experienced hunters. I know a guy that goes to Colorado every year, for a week, and hunts public land for elk. It's usually him and his dad, or a buddy. They stay out all week. He's a great hunter, but last year in deer camp, he was checking zero on his 30-06, with his scope at 12x, adjustable odjective set at 200 yds. Next morning, a bruiser of a 12 pointer jumped up at 20 yds, and he'd forgotten to reset his scope, and all he saw was a blur of woods. He couldn't see to make the shot. We found out what the deer was because to guy on the next ridge dropped it with one shot of his old Savage bolt action 30-30 with a 100 yds shot, with a 2.5x Lyman scope.
To sum up, I would be more than comfortable with the 4x scope on your rifle.
