Grandad,
The document referred to in the following entry from the Defense Technical Information Center is from 1961, but it makes clear that there was at least a 100 round canvas magazine at some point in the M60's history. I'll keep looking for photographic evidence, though.
Ray
Accession Number : AD0259416
Title : EVALUATION OF MODIFIED FEED SYSTEM FOR GUN, MACHINE, 7.62MM, M60
Corporate Author : ARMY ARCTIC TEST CENTER FORT GREELY ALASKA
Report Date : 10 JUL 1961
Pagination or Media Count : 1
Abstract : The M60 Machine Gun was equipped with the test item, with 100 rounds of ammunition in a T-7 bandoleer attached, weighed 1.2 lbs. less than an M60 Machine Gun equipped with the current mounting bracket and canvas magazine filled with 100 rounds of ammunition. Approximately 12,000 rounds were fired from each of four M60 machine guns equipped with modified feed systems. The ammunition was fed from various containers that were not attached to the gun. No interference from the hook on the modified systems was noted. No difference in the ease of attachment of a loaded T-7 bandoleer to the hooks was observed. The Type A Modified Feed System, when used in conjunction with a bandoleer identical to the Machine Gun Bandoleer, T-7, was superior to the mounting bracket-canvas magazine combination used on the Gun, Machine, 7.62mm, M60, and is suitable for Army use. The Type B Modified Feed System for the Gun, Machine, 7.62mm, M60, is not suitable for use with the Gun, Machine, 7.62mm, M60. The design of the Machine Gun Bandoleer, T-7, is suitable for use with the Type A Modified Feed System for the Gun, Machine, 7.62mm, M60. However, this bandoleer lacks the desired durability. (Author)
Descriptors : *AUTOMATIC WEAPONS, *AMMUNITION FEED MECHANISMS, GUNS, LOADERS, SMALL ARMS.
Distribution Statement : APPROVED FOR PUBLIC RELEASE