More changes would be needed than direct uniform scaling - .22lr is rimfire, whereas .45acp is centerfire, for example, and their aspect ratios are different. The mass and strength of uniformly scaled-down parts also might not match the recoil and pressure provided by the smaller round, and might result in failure to reliably cycle the action or the gun bursting if the mismatch is too much.
Training and familiarization helped me a lot with that exact feeling. I had the same feeling about circular/table saws. My dad was a carpenter, and those things freaked me the hell out - one tiny mistake could have devastating consequences, and that was all I could think about when I was around them. But with careful instruction and exposure, learing to use and be more comfortable with them, that feeling was gradually replaced by calm and confidence, and they changed in my mind from these objects of terror into valuable tools. There was still fear, but it was a healthy, respectful fear.
I went through the exact same process with guns as well. Some classes with a good instructor, giving you a chance to get more comfortable and familiar before you bring a gun into your home, could help a lot.