Talk with smith and let him/her see what you have.
Explain in detail what you want. If you agree to have work done, put the exact work to be done in writing.
If that is a .22 upper on the gun now, you need more parts to make it function in a safe manner.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)