When I put my key into the ignition it wont turn,after a few hard turns the key

Yea I did for the longest all my keys for my shop,recently last two months narrowed them down but it had been yrs so was just making sure that me swapping that lock cylin..Appreciateder out would fix this appreciate it,any other tip or hints towards that would help..thx

Follow directions, TAKE YOUR TIME and be sure everything is lined up correctly. Good luck