They lost to FN over a technicality, i think they failed to provide a blank firing device or something stupid like that. Its actually has a very good reputation in the US, if we had asked robinson to manufacture here, they would have done it for half the price quoted by the russians.
Yes it was one of finalist among that SCAR program where current FN SCAR won when this was booted out because it did not have Blank Firing Adapter available for it when the final trials happened; owner of the company, Alex Robinson, used to mention that US SOCOM put requirement that the rifle should be supporting new underbarrel grenade launcher with computerized sights (later labelled as ELGM) which wasted about two and half month of time for Robinson Arms to adjust their design to make it suitable to a grenade launcher - and in all these hurry they *ahem* 'forgot' to deliver a BFA to 5.56mm version on time ALTHOUGH the barrel had same muzzle device as M16 and that same pattern of BFA that goes on existing M16s-M4s was suitable to it - but over non-delivery of BFA it was rejected from competition and FN's design became SCAR
another competitor that quickly got rejected from SCAR trials, was some "Cobb" design which was more or less...this...
basically a three-section receiver AR-10/15 fork with replaceable magazine well and upper section (and upper section internals like bolts and/or bolt carriers) for different calibres, Cobb manufactured some prototypes in,
5.56 NATO, Cobb MCR100
7.62 NATO, Cobb MCR200
Cobb MCR300 in .30-06 and Cobb MCR400 in .300 Winchester Magnum
Cobb MCR400 in .338 Lapua Magnum, notice side-mounted magazine well on upper receiver
but it didn't stop here, Cobb promised lots of configurations for these MCR100 to MCR400 in different calibres such as;
MCR100 -> 9×19mm; 45ACP; .223 Remington/5.56×45mm; 7.62×39mm; .50 Beowulf; 6.5 Grendel
MCR200 -> .308/7.62×51mm; .243 Winchester; .22-250; .220 Swift; 6mm Remington; 250-3000 Savage; 300 Savage, 7mm-08 Remington
MCR300 -> .30-06; 8×57mm; 240 Weatherby Magnum; 257 Roberts; 25-06 Remington; 270 Winchester; 7×57mm Mauser; 284 Winchester; 280 Rem ; .35 Whelen; 6.5×284; 6.5×55 Swedish Mauser; 6×284mm; 260 Remington; 270 Winchester Short Magnum; 7×64mm BR
MCR400 -> 257 Weatherby Magnum; 264 Winchester Magnum; 270 Weatherby Magnum; 7mm Remington Magnum; 7mm Weatherby Magnum; 300 H&H Magnum; 300 Winchester Magnum; 300 Rem; 300 Weatherby Magnum; 308 Norma Magnum; 338 Winchester Magnum; 338 LAPUA Magnum; 338 Remington Ultra Magnum; 340 Weatherby Magnum; 350 Remington Magnum; 35&H Magnum; 8mm Remington Magnum; 378 Weatherby Magnum; 416 RIGBY; 416 Remington Magnum; 416 Taylor; 458 Winchester Magnum
yeh Cobb toh pura jhakeera de rha thaa ek hi line ke under...
needlessly to say, it did not succeed and mostly remained to prototype levels; but we can surely say these efforts did not completely go in vein as in future or in our current time we are already seeing AR pattern rifles in diverse calibres, mostly covering these calibres mentioned here
there was also some bolt-action rifle prototype in heavy calibres, i think .50 BMG by this Cobb
source ->
https://defensereview.com/cobb-scar-candidatemcr-prototype-weapons-at-shot-show-2005/
another noteworthy SCAR competitor was;
XM8 SCAR prototype
basically a fork of G36 // XM-8 design with promises for multi-calibre options in future and a new handguards + receiver design with picatiny rails on top