I agree that shooting more definitely helps a lot. I put thousands of rounds through my comp bolt 223 rifle a year, all positional shooting. I agree that all that has a positive affect on your abilities. I do know that shooting a 223 is far more forgiving for shooting form errors that larger calibers. My example to would be this, if you are not driving your rifle correctly it is possible to miss high, low, left or right and it’s you and not your environment so making a correction is very difficult. I do a lot of practice with my 223 as well but shooting my 25 creed is better for me to practice my form because it tends to show my bad habits. I suggested a 308 because the components are readily available and similar recoil.
Anyway hope this was helpful and I’m not trying to be a know it all. Just trying to give up one person’s opinion.