<PAGE>   1


EXHIBIT 10.01-05                                                  EXECUTION COPY



                                            FOURTH AMENDMENT dated as of
                                    February 14, 1997 (this "Fourth Amendment"),
                                    to the Credit Agreement dated as of July 31,
                                    1996 (the "Credit Agreement"), among
                                    Firearms Training Systems, Inc., a Delaware
                                    corporation ("FATS"), the Lenders (as
                                    defined therein) and NationsBank, N.A.
                                    (South), as Agent, Swingline Lender and
                                    Issuing Bank (each as defined therein).

         The parties hereto have agreed, subject to the terms and conditions
hereof, to amend the Credit Agreement as provided herein.

         Capitalized terms used and not otherwise defined herein shall have the
meanings assigned to such terms in the Credit Agreement (the Credit Agreement,
as amended by, and together with, this Fourth Amendment, and as hereinafter
amended, modified, extended or restated from time to time, being called the
"Amended Agreement").

         Accordingly, the parties hereto hereby agree as follows:

         SECTION 1.01. Amendments to Section 1.01. (a) The definition of
"Additional Drop Down Margin" in Section 1.01 of the Credit Agreement is hereby
amended by deleting the date "February 15, 1997" in the second line thereof and
substituting the date "May 16, 1997" in lieu thereof.

         (b)   The definition of "Permitted Drop Down Transaction" in Section 
1.01 of the Credit Agreement is hereby amended by deleting the date "February
15, 1997" in clause (i)(B) of the proviso thereto and substituting the date "May
16, 1997" in lieu thereof.

         SECTION 1.02. Representations and Warranties. The Borrower hereby
represents and warrants to the Agent and the Lenders, as follows:

               (a) The representations and warranties set forth in Article III 
         of the Amended Agreement and the representations and warranties of the
         Borrower and the other Loan Parties set forth in the other Loan
         Documents are true and correct in all material respects on and as of
         the date hereof and on and as of the Fourth Amendment Effective Date
         (as defined below) with the same effect as though made on and as of the
         date hereof or the Fourth Amendment Effective Date, as the case may be,
         except to the extent such representations and warranties expressly
         relate to an earlier date (in which case such representations and
         warranties are true and correct in all material respects on and as of
         such earlier date).

               (b) On the date hereof and on the Fourth Amendment Effective 
         Date, no Default or Event of Default has occurred and is continuing.

               (c) The execution, delivery and performance by the Borrower of
         this Fourth Amendment have been duly authorized by the Borrower.


<PAGE>   2

               (d)     This Fourth Amendment constitutes the legal, valid and 
         binding obligation of the Borrower, enforceable against it in
         accordance with its terms.

               (e)     The execution, delivery and performance by the Borrower 
         of this Fourth Amendment will not (i) violate, (A) any provision of
         law, statute, rule or regulation, (B) any provision of the certificate
         of incorporation or by-laws of the Borrower, (C) any order of any
         Governmental Authority or (D) any provision of any indenture, agreement
         or other instrument to which the Borrower or any of the Loan Parties is
         a party or by which any of them or any of their property is or may be
         bound, (ii) be in conflict with, result in a breach of or constitute
         (alone or with notice or lapse of time or both) a default or give rise
         to increased, additional, accelerated or guaranteed rights of any
         person under any such indenture, agreement or other instrument or (iii)
         result in the creation or imposition of any Lien upon or with respect
         to any property or assets now owned or hereafter acquired by the
         Borrower or any of the other Loan Parties.

         SECTION 1.03. Effectiveness. This Fourth Amendment shall become
effective as to the Lenders only upon satisfaction of the following conditions
precedent (the first date upon which each such condition has been satisfied
being herein called the "Fourth Amendment Effective Date"):

               (a)     The Agent shall have received duly executed counterparts
         of this Fourth Amendment which, when taken together, bear the
         authorized signatures of the Borrower and the Lenders.

               (b)     The representations and warranties set forth in Section
         1.02 shall be true and correct on and as of the Fourth Amendment
         Effective Date.

               (c)     The Lenders shall have received such other documents,
         legal opinions, instruments and certificates as they shall reasonably
         request and such other documents, legal opinions, instruments and
         certificates shall be satisfactory in form and substance to the Lenders
         and their counsel. All corporate and other proceedings taken or to be
         taken in connection with this Fourth Amendment and all documents
         incidental thereto, whether or not referred to herein, shall be
         satisfactory in form and substance to the Lenders and their counsel.

         SECTION 1.04. APPLICABLE LAW. THIS FOURTH AMENDMENT SHALL BE CONSTRUED
IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK.

         SECTION 1.05. Expenses. The Borrower shall pay all reasonable
out-of-pocket expenses incurred by the Agent and the Lenders in connection with
the preparation, negotiation, execution, delivery and enforcement of this Fourth
Amendment, including, but not limited to, the reasonable fees and disbursements
of counsel. The agreement set forth in this Section 1.05 shall survive the
termination of this Fourth Amendment and the Amended 



                                      2
<PAGE>   3

Agreement.

         SECTION 1.06. Counterparts. This Fourth Amendment may be executed in
any number of counterparts, each of which shall constitute an original but all
of which when taken together shall constitute but one agreement.

         SECTION 1.07. Credit Agreement. Except as expressly set forth herein,
the amendments provided herein shall not by implication or otherwise limit,
constitute a waiver of, or otherwise affect the rights and remedies of the
Lenders, the Agent or the other Secured Parties under the Amended Agreement or
any other Loan Document, nor shall they constitute a waiver of any Default or
Event of Default, nor shall they alter, modify, amend or in any way affect any
of the terms, conditions, obligations, covenants or agreements contained in the
Amended Agreement or any other Loan Document. Each of the amendments provided
herein shall apply and be effective only with respect to the provisions of the
Amended Agreement specifically referred to by such amendment. Except as
expressly amended herein, the Amended Agreement shall continue in full force and
effect in accordance with the provisions thereof. As used in the Amended
Agreement, the terms "Agreement", "herein", "hereinafter", "hereunder", "hereto"
and words of similar import shall mean, from and after the date hereof, the
Amended Agreement.




                                      3
<PAGE>   4



         IN WITNESS WHEREOF, the parties hereto have caused this Fourth
Amendment to be duly executed by their duly authorized officers, all as of the
date first above written.



                                           FIREARMS TRAINING SYSTEMS, INC.

                                           By:  /s/  David A. Apseloff
                                              ----------------------------------
                                           Name:    David A. Apseloff
                                           Title:   Chief Financial Officer

                                           NATIONSBANK, N.A. (SOUTH), as Agent,
                                           Issuing Bank and Swingline Lender 
                                           and as a Lender

                                           By:  /s/  Greg McCrery
                                              ----------------------------------
                                           Name:    Greg McCrery
                                           Title:   Vice President

                                           FIRST BANK NATIONAL ASSOCIATION

                                           By:  /s/  Mark R. Olman
                                              ----------------------------------
                                           Name:    Mark R. Olman
                                           Title:   Vice President

                                           FIRST SOURCE FINANCIAL LLP,
                                           by First Source Financial, Inc., as 
                                           Agent/Manager

                                           By:  /s/  Gary L. Francis
                                              ----------------------------------
                                           Name:    Gary L. Francis
                                           Title:   Senior Vice President

                                           BHF-BANK AKTIENGESELLSCHAFT

                                           By:  /s/  Herman Skouis
                                              ----------------------------------
                                           Name:    H. Skouis
                                           Title:   Assistant Vice President

                                           By:  /s/  Evon Contos
                                              ----------------------------------
                                           Name:    Evon Contos
                                           Title:   Vice President

                                           CREDITANSTALT CORPORATE FINANCE, INC.

                                           By:  /s/  Carl G. Drake
                                              ----------------------------------
                                           Name:    Carl G. Drake
                                           Title:   Senior Associate
<PAGE>   5

                                           By:  /s/  Robert M. Biringer
                                              ----------------------------------
                                           Name:    Robert M. Biringer
                                           Title:   Executive Vice President