After waiting for months for the DD RIS II FSP to become available again, and getting burned by procuring through ebay only to learn that it's actually an airsoft replica ("we told you so, Carl!"), the USMC gave up on the RIS II and simply bought the Ergo thingy that bolts on to your FSP.

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Source: https://www.dvidshub.net/image/53616...tinum-ren-2019

And, for those that didn't know this thing existed: https://www.ergogrips.net/shop/ergo-m4-4-rail/