<SUBMISSION>
<ACCESSION-NUMBER>0001181431-14-010284
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20140227
<FILING-DATE>20140303
<DATE-OF-FILING-DATE-CHANGE>20140303
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>AMERICAN PACIFIC CORP
<CIK>0000350832
<ASSIGNED-SIC>2810
<IRS-NUMBER>596490478
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>0930
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>3883 HOWARD HUGHES PARKWAY
<STREET2>STE 700
<CITY>LAS VEGAS
<STATE>NV
<ZIP>89169
<PHONE>7027352200
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>3883 HOWARD HUGHES PARKWAY
<STREET2>STE 700
<CITY>LAS VEGAS
<STATE>NV
<ZIP>89169
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Scharfman Scott
<CIK>0001435257
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-08137
<FILM-NUMBER>14661246
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>382 GREENWICH AVE
<STREET2>SUITE ONE
<CITY>GREENWICH
<STATE>CT
<ZIP>06830
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LYNCH THOMAS E
<CIK>0001244666
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-08137
<FILM-NUMBER>14661247
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>382 GREENWICH AVE
<STREET2>SUITE ONE
<CITY>GREENWICH
<STATE>CT
<ZIP>06830
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Mill Road Capital II GP LLC
<CIK>0001550728
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-08137
<FILM-NUMBER>14661248
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>382 GREENWICH AVE.
<STREET2>SUITE ONE
<CITY>GREENWICH
<STATE>CT
<ZIP>06830
<PHONE>203-987-3500
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>382 GREENWICH AVE.
<STREET2>SUITE ONE
<CITY>GREENWICH
<STATE>CT
<ZIP>06830
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Mill Road Capital II, L.P.
<CIK>0001550729
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-08137
<FILM-NUMBER>14661249
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>382 GREENWICH AVE.
<STREET2>SUITE ONE
<CITY>GREENWICH
<STATE>CT
<ZIP>06830
<PHONE>203-987-3500
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>382 GREENWICH AVE.
<STREET2>SUITE ONE
<CITY>GREENWICH
<STATE>CT
<ZIP>06830
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd404107.xml
<DESCRIPTION>APFC FORM 4 - 2
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-02-27</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000350832</issuerCik>
        <issuerName>AMERICAN PACIFIC CORP</issuerName>
        <issuerTradingSymbol>APFC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001550729</rptOwnerCik>
            <rptOwnerName>Mill Road Capital II, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>382 GREENWICH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE ONE</rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001550728</rptOwnerCik>
            <rptOwnerName>Mill Road Capital II GP LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>382 GREENWICH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE ONE</rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001244666</rptOwnerCik>
            <rptOwnerName>LYNCH THOMAS E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>382 GREENWICH AVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE ONE</rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001435257</rptOwnerCik>
            <rptOwnerName>Scharfman Scott</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>382 GREENWICH AVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE ONE</rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-02-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>U</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>916690</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares were held directly by Mill Road Capital II, L.P. (the &quot;Fund&quot;).  Mill Road Capital GP II LLC (the &quot;GP&quot;) is the sole general partner of the Fund with the power to vote (or direct the vote of), and to dispose (or direct the disposal) of, these shares. Thomas E. Lynch and Scott P. Scharfman are Management Committee Directors of the GP with shared authority to vote (or direct the vote of), and to dispose (or direct the disposal) of, these shares. Each of the Reporting Persons disclaims beneficial ownership of these shares, except to the extent of his or its pecuniary interest therein, if any.</footnote>
        <footnote id="F2">On February 27, 2014, an acquisition subsidiary affiliated with and controlled by H.I.G. Capital, LLC, a Delaware limited liability company, acquired all of the outstanding shares of the Issuer's common stock via merger at a price of $46.50 per share. The Fund has not accepted the $46.50 per share being paid in the merger and is instead seeking a determination, in accordance with Delaware law, of the fair value of the shares of the Issuer's common stock that the Fund held as of immediately prior to the consummation of the merger.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Scott P. Scharfman, Management Committee Director of sole general partner on behalf of Mill Road Capital II, L.P.</signatureName>
        <signatureDate>2014-03-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott P. Scharfman, Management Committee Director on behalf of Mill Road Capital II GP LLC</signatureName>
        <signatureDate>2014-03-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott P. Scharfman on behalf of Thomas E. Lynch, by power of attorney</signatureName>
        <signatureDate>2014-03-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott P. Scharfman</signatureName>
        <signatureDate>2014-03-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
