EXHIBIT 10.7

Execution Copy
A.M. Castle & Co.
1420 Kensington Road, Suite 220
Oak Brook, IL 60523

February 8, 2016

SGF, LLC
30 North LaSalle Street, Suite 1232
Chicago, IL 60602
Ladies and Gentlemen:

Reference is hereby made to that certain Purchase Agreement, dated as of
February 8, 2016 (the “Purchase Agreement”), by and among SGF, LLC, an Illinois
limited liability corporation (“SGF”), Mackay Shields LLC (“Mackay Shields”),
and A.M. Castle & Co., a Maryland corporation (the “Company”), pursuant to which
SGF has agreed to purchase from certain accounts for which Mackay Shields holds
contractual and investment authority $34,728,000 aggregate principal amount of
the Company’s 12.75% Senior Secured Notes due 2016 (the “Purchased Notes”).
Capitalized terms used without definition in this letter (this “Letter
Agreement”) shall have the meanings given to such terms in the Purchase
Agreement.

The undersigned, for their mutual convenience and for good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged,
agree as follows:
1.SGF shall, prior to the Expiration Date (as defined in the Offering
Memorandum), validly tender and not withdraw the Purchased Notes (and deliver a
corresponding consent in respect thereof) into the Exchange Offer in accordance
with requirements described in the Offering Memorandum. SGF further covenants
that after tendering the Purchased Notes in the Exchange Offer, SGF shall not
withdraw or revoke, or cause to be withdrawn or revoked, in whole or in part,
its tender or consent of Purchased Notes prior to the expiration of the Exchange
Offer and the issuance of new notes (the “New Notes”) by the Company in exchange
for Purchased Notes pursuant to the terms and conditions of the Exchange Offer
as provided in the Offering Memorandum.

2.In consideration of SGF’s covenant in Section 1 hereof, and subject to
compliance therewith, (i) the Company agrees that it shall reimburse SGF for all
reasonable and documented fees of one legal counsel to SGF incurred in
connection with the negotiation of the Purchase Agreement, this Letter Agreement
and other reasonably related matters, (ii) notwithstanding any term or condition
of the Exchange Offer, the Company shall pay to SGF on the Settlement Date (as
defined in the Offering Memorandum) the Consent Payment (as defined in the
Offering Memorandum) that would have been payable with respect to the Purchased
Notes if the Purchased Notes had been validly tendered and not withdrawn as of
the Early Tender Date (as defined in the Offering Memorandum) and accepted for
exchange by the Company pursuant to the Exchange Offer and (iii) on the
Settlement Date (as defined in the Offering Memorandum) SGF will receive from
the Company the same proportionate consideration with respect to its validly
tendered (and not withdrawn) Purchased Notes that other investors who validly
tendered (and did not withdraw) their Notes into the Exchange Offer by the Early
Tender Date (as defined in the Offering Memorandum) received on the Early
Settlement Date (as defined in the Offering Memorandum). Each global note
representing New Notes issued on the Settlement Date shall have a CUSIP number
that is the same as the CUSIP number on a global note representing New Notes
issued on the Early Settlement Date.

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3.This Letter Agreement may be amended only upon written approval of each of the
parties hereto.

4.This Letter Agreement shall in all respects be construed in accordance with
and governed by the substantive laws of the State of New York, without reference
to its choice of law rules.

5.This Letter Agreement may be executed in counterparts, each of which shall be
deemed an original, but all of which taken together shall constitute one and the
same instrument. Any counterpart or other signature hereon delivered by
facsimile or any standard form of telecommunication or e-mail shall be deemed
for all purposes as constituting good and valid execution and delivery of this
Letter Agreement by such party.

[Rest of Page Intentionally Left Blank]

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Please acknowledge your agreement and acceptance of the foregoing by
countersigning this letter in the space provided below.

Yours sincerely,
A.M. CASTLE & CO.
By: /s/ Marec E. Edgar    
Name: Marec E. Edgar
Title: Executive Vice President, General Counsel, Secretary & Chief
Administrative Officer

ACKNOWLEDGED AND AGREED AS OF THE DATE HEREOF:
SGF, LLC
By: /s/ Reuben S. Donnelley
Name: Reuben S. Donnelley
Title: Managing Member
Date: February 8, 2016

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