Said to be a Famas previously owned by Syrian President Bashar Al Assad.
At IDEX (at least probably at IDEX) Sig showed off an XM7 Iteration with no folding stock and an unsuppressed weight of 7.7lbs
Chopped AK-12M1
ASM with an M-lok rail AND the clamp on rail thingy
US Serviceman holding an RPL-7 machinegun, probably one of the first if not the first American to ever do so
Double barrel semi auto
Colt CMG-3
Some wacky 1911 conversion kit concepts
Daewoo K2 prototypes in 7.62
Someone's selling a Colt ACR upper (or a very convincing counterfeit) on gunbroker
Bottom gun is a "modernized" Argentinian FMK-3
Mossberg 500 Bullpup seized from a Venezuelan prison (South American prisoners seem to have a tendency to have lots and lots of guns while in prison yet make no effort to escape)
CS/LS06 in Venezuela

And a Vektor CR-21
.40 S&W FAL based PCC prototype
Apparently Springfield is going to be importing this very ugly PCC which HS Produkt calls the "Kuna". Springfield will probably give it a dumb name. Supposedly roller delayed with proprietary mags. Notable lack of GRIP ZONE
Calico and a rusty Spas-12 seized from/surrendered by Colombian rebels
Lee Enfield converted to 54R using a PKM barrel and Draganouv mags
@Club Sandwich
It has been recently brought to my attention that both the M60 series of machineguns as well as the Sig MCX/Spear series of rifles utilize a short stroke piston system that do not include piston return springs but have pistons are instead forced forwards by the forward movement of either the op rod or a protrusion on the recoil spring guide assembly. While I am not an engineer It would seem to me that this is a superior system as it includes less parts and one less spring that you need to worry about getting hot, getting damaged and eventually replacing. Is there any particular reason to go with a spring including design over a "free floating" one? off the top of my head systems with springs are much more common.