I found this on another forum.
"I called Anniston DRMO this afternoon and spoke with the individual who has handled most of the listings for material under the 1005 FSC Code. He has been there for two years and has not had any large sales of magazines. However, he does know that pistol magazines have been sold in small quantities (200-300) at Anniston and at other DRMO sites. He gave me the website to look at DRMS sales: http://www/drms.dla.mil
I went there and found that the number on the bottom of the magazine in question is a VALID partial NSN. The whole NSN is:
1005-00-5508694. The nomenclature for the item is: Magazine, Cartridge, Steel, Phosphate Coated, 7 Cartridge Capacity
I also discovered a site to identify the other numbers on the bottom of the magazine. They are generally referred to as "Cage Codes." The site is: http://www.dlis.dla.mil/CAGESearch
19200 = US Army Armaments Reasearch and Development Command, New Jersey (NOTE: This code formerly assigned to US Frankfort Arsenal)
30745 = Mason-Rust Co., Pittsburgh, PA 15200
Mason-Rust Company is no longer in business. It was absorbed into Rust Engineering in the 80's and no longer exists as a separate entity.
Based on all of the above, the good news is that, YES, these are real USGI surplus items.
As for the DRMO Disposal Codes, it turns out that Code B items can be disposed of intact if they pose "no significant military effect."