FullText Index on VARBINARY column: how to find string with dot
Sorry this might not be an answer but I cannot put this in comment.  Based on the comment by OP @Jefferson (as an answer to my comment) I could not reproduce the behavior.  I can get a record back with where clause exactly matching the value.

I tested this with following code (copied and modified from here)

CREATE TABLE Department 
   (DepartmentID INT IDENTITY CONSTRAINT DepartmentPK PRIMARY KEY, 
    NAME NVARCHAR(50),
    File_txt NVARCHAR(50));
GO
INSERT INTO Department (NAME, File_txt) VALUES ('OP1', 'CORP-MMM-456.245');
INSERT INTO Department (NAME, File_txt) VALUES ('OP2', 'CORP-MMM-456.246');
INSERT INTO Department (NAME, File_txt) VALUES ('OP3', 'CORP-MMM-456.247');
INSERT INTO Department (NAME, File_txt) VALUES ('OP4', 'CORP-MMM-456.245.246');

Go
CREATE FULLTEXT CATALOG ComplexFTS AS DEFAULT;
GO
CREATE FULLTEXT INDEX ON Department(File_txt LANGUAGE 1033 /* 0 = Neutral, 1033 = American English  */)  
KEY INDEX DepartmentPK WITH (STOPLIST = OFF); /* Or use (stoplist = Off) for no stoplist */
GO
WAITFOR DELAY '00:00:05';
GO
SELECT * FROM Department WHERE CONTAINS (File_txt,'"CORP-MMM-456.*"');
SELECT * FROM Department  WHERE CONTAINS(File_txt,'CORP-MMM-456.245')
GO


This is what I get as my result set.



Clean up code.

DROP FULLTEXT INDEX ON Department;
GO
DROP FULLTEXT CATALOG ComplexFTS;
GO
DROP TABLE Department;
GO