Thanks for the screenshot of the M1 yl9961027 I think it's pretty cool, at the very least it does show how moddable SFK42 really is and might be a good indicator of possiblites with Steel Armor Blaze of War.
Btw I do remember someone was working on a M4 model at the sukhoi.ru forum quite awhile back, heres the 3d model.
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More recently Watchman was also working on a M-10, Firefly and a M4A3 at the Graviteam forums
http://graviteam.com/forum/index.php?topic=1115.0 But so far nothing more has come of it from the sukhoi.ru forum and Watchman went MIA