How did the use of repeating rifles change the American Civil War?

I am not 100% sure because this from an online source and the web can't always be trusted. But, from what I have read, repeating rifles had no significance used in the Civil War! They could not be mass produced because the government didn't do anything about it. So, they were not even looked at as a wonder weapon. IF YOU HAVE A BETTER ANSWER FROM A TRUSTWORTHY SOURCE, DELETE MY COMMENT!!!

The Spencer repeating rifle made little impact on the war, The standard issue muzzle loaders were still the main firearm used by both sides.