Anyone pick up the most recent Small Arms Review and notice the funky looking front sight base/gas block  on the Colt M4 that's pictured in the review of HK's AGL 40mm launcher?

The M4's lower is clearly a Colt and the upper has the CAF markings of a Colt upper forged by Acoa.  But the FSB is really throwing me for a loop.  

Could this be the much rumored gas piston/op-rod M4 upper from HK?

Josh

It didnt say, but would think that it was just another type of front sight/gas block for mounting the HK AG-C.

P.31 last paragraph describes how the AG36 attaches to the G36, it sounds like the front sight may just be an H&K variant that allows a similar QD feature, but on the M4.