In the example below, I've created a stored procedure called [acct_staging_truncate] which truncates a table. The user 'acctmaint' is db_owner, and user 'JoeSchmo' is a public member with no permissions except execution on the procedure [acct_staging_truncate].

create procedure acct_staging_truncate

with execute as 'acctmaint'

as

truncate table acct_staging;

go

grant exec on acct_staging_truncate to JoeSchmo;

go

I've confirmed that JoeSchmo can execute the procedure successfully, but he can't truncate, select, or anything else directly on the table.