Buying on spec - - -
Good plan, Frosty.
If you intend to get a full auto, then don't bother with any TSMG box mag with an oval mag latch hole in it. It has been modified for use in the semi-only pieces, and may or may not work in a full suto gun. Also, people feel that those for the semi-only guns command higher prices than the others.
Generally, the 1928 (and earlier 1921) guns bring a higher price than the M1 and M1A1 WW-II guns. HOWEVER--If you're lucky enough to locate an affordable 1928 or 1928-A1 gun, these were used diring WW-II as well--just, normally, with the horizontal foreend. But the British forces, particularly, also used some with the vertical foreend. As previously mentioned, the 1928-series would also accept the 50-round drums.
If your main interest is the TSMG as used by the military, you can pretty well forget the 100-round drum. I don't think these were ever used by the U.S. forces.
Interestingly, the FIRST military use of the TSMG was the 1921 model, used by the Irish. One may debate the legitimacy of the Irish Rebel forces as a proper army, but, after independence, many of their guns went to the Republic of Ireland military stores. I believe they may have had some 100-round drums, which, BTW, were never intended for the 1928 models.
(Those better informed--Please forgive any misuse of terms concerning Ireland and her properly-constituted military forces. I an NOT talking about any terroristic organizations in Ireland.)
Both 20 and 30-round mags were used by US military in WW-II. Not sure when the 30-round came into use.
Good luck on your search for a full-auto.
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