Just use steel. It is cheap enough.

http://www.smallparts.com/products/descriptions/shss.cfm

For a proper job, send it a good gunsmith. I use Dave Norin:
DavidNorin@aol.com
(847) 662-4034
c/o Schranks Smoke n Gun
2010 Washington Street, IL 60085-5132
Waukegan

He has one my guns now that was loose. I have used him in the past. He is very good. His prices are reasonable for the work done. He will not solder in a shim...

Pete