I put this in an old thread but thought it was worth it's own.

Bureau is making wholesale changes to their agent issued M4s. Uppers are being replaced with Colt units that have 11.5" (I believe) barrels, Troy alpha rails along with Magpul CTR stocks. Also the upper is shipped with an Aimpoint T2 (replacing their Eotechs) that sits on a Daniel Defense mount. VTAC 2 point slings are common but have seen some others depending on personal preference. Seems to be a very nice shooting, very light setup. Saw it in action first time this week during some range time with the NY office SWAT team.

As an aside they have also introduced a POW (personally owned weapon) AR that is a Colt LE6920, 16" barrel, Troy alpha rails with the allowed accessory list including a Troy lopro QD swivel mount, an inforce white/IR wml, VTAC sling, Magpul CTR stock, Hogue pistol grip and the Aimpoint H1, H2, T1 or T2 and DD mount. Designated the LE6920-FBP1. So side-by-side, it looks like the big brother of the Agent issued SBR. Or would that make it the "little" brother?

I'll post pics when mine arrives. My understanding is it goes from Colt to the armorers at Quantico and then to your field office's range as you must qualify with it before you can take possession. Armorers have to install the grip and the swivel mount and the user, with area's firearms instructor supervision, installs anything else.

(also allowed Troy "squid grips" and Mako PTK, a rather unwieldy looking AFG)