Special Operations Peculiar Tube Modification…yes, I just made that up.
But check out the pic above – a JP Enterprises tube front end, in place of a RIS II (along with an ACE SOCOM stock).
And take a look at the pics below. Just a few of the many confirming instances of the broad range of tube front ends In The Wild: either issued, like Delta’s Geissele SMRs and the Aussie Troy rails we’re seeing more and more of; or individual/unit purchases of the You Dream It, We Build It variety.
How long before a tube rail turns up in a Block III increment?