-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 JIGUjf5jHgNCPang5LEu7OK17GP6V9Eg7uIBnsumMaUAsFAR86P6PIVyAKPYl034
 SN+tV3+QxK6d02duv4Whrw==

<SEC-DOCUMENT>0001104659-05-020734.txt : 20050505
<SEC-HEADER>0001104659-05-020734.hdr.sgml : 20050505
<ACCEPTANCE-DATETIME>20050505133745
ACCESSION NUMBER:		0001104659-05-020734
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050503
FILED AS OF DATE:		20050505
DATE AS OF CHANGE:		20050505

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Ross Keith D
		CENTRAL INDEX KEY:			0001305457

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10582
		FILM NUMBER:		05802622

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		9523513086

	MAIL ADDRESS:	
		STREET 1:		5050 LINCOLN DRIVE
		CITY:			EDINA
		STATE:			MN
		ZIP:			55436

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ALLIANT TECHSYSTEMS INC
		CENTRAL INDEX KEY:			0000866121
		STANDARD INDUSTRIAL CLASSIFICATION:	GUIDED MISSILES & SPACE VEHICLES & PARTS [3760]
		IRS NUMBER:				411672694
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		5050 LINCOLN DRIVE
		CITY:			EDINA
		STATE:			MN
		ZIP:			55436-1097
		BUSINESS PHONE:		9523513000

	MAIL ADDRESS:	
		STREET 1:		5050 LINCOLN DRIVE
		CITY:			EDINA
		STATE:			MN
		ZIP:			55436-1097
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-05-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000866121</issuerCik>
        <issuerName>ALLIANT TECHSYSTEMS INC</issuerName>
        <issuerTradingSymbol>ATK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001305457</rptOwnerCik>
            <rptOwnerName>Ross Keith D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ALLIANT TECHSYSTEMS</rptOwnerStreet1>
            <rptOwnerStreet2>5050 LINCOLN DRIVE</rptOwnerStreet2>
            <rptOwnerCity>EDINA</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55436-1097</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr VP Gen Counsel &amp; Secy</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-05-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>22</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4118</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-05-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>22</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>68.85</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4096</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>339.9563</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-05-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1478</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1478</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1550.21</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Shares simultaneously acquired and disposed represent shares withheld to pay Medicare taxes in connection with the grant of a Performance Share Award (PSA) and the reporting person's deferral of the remaining performance shares under the Issuer's Nonqualified Deferred Compensation Plan (NQDCP) (reported in Table II of this Form).</footnote>
        <footnote id="F2">The amount reported includes 3,000 shares subject to certain restrictions (including possible forfeiture) applicable to restricted stock grants under the Issuer's 1990 Equity Incentive Plan and 87 shares held in the Issuer's Employee Stock Purchase Plan as of March 31, 2005..</footnote>
        <footnote id="F3">The Phantom Stock Units were credited to the reporting person's account in the Issuer's Nonqualified Deferred Compensation Plan (NQDCP) in lieu of the grant by the Issuer of a Performance Share Award (PSA) under the Issuer's 1990 Equity Incentive Plan.  The number of units credited to the reporting person's account was determined on a 1-for-1 basis equal to the number of shares of common stock that would have been granted for the PSA (1500), reduced by the number of units having a value equal to the Issuer's Medicare tax withholding obligation as a result of the deferral of the payment of the PSA.  The units are to be settled 100% in cash following the reporting person's termination of employment or such other date specified by the reporting person.  However, the reporting person may elect to transfer funds into other investment accounts within the NQDCP.  NQDCP participants may transfer funds into alternative investment accounts during a 10-day window period each quarter.</footnote
>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Keith D. Ross</signatureName>
        <signatureDate>2005-05-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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