The online mecca for gun nuts – TheFirearmBlog.com – has featured a rather nifty weapons modification that is of interest to both RS and airsoft fans alike. The multi-caliber ‘lower’ is what it says, a means of getting the SCAR rifle to accept a variety of different calibres simply by replacing the lower half of the weapon.
This novel means of switching calibres has been something of a holy grail in military terms extending, as it does, the fashionable idea of the 'modular weapon' (as – probably – imagined by Eugene Stoner in the 1960s). The FN SCAR series of rifles does go so far in offering a modular weapon, albeit in an off-the-shelf format (in that you can have any shape or size of assault rifle format you can imagine based on a basic sub-set of related components) but the gun does only come in the two NATO calibres – 5.56mmm and 7.62mm.
The need for a gun capable of handling various calibres – but most notably those of the 'enemy' – came to prominence during the early Afghan campaign where US Special Forces complained that while they were running short of 5.56mm rounds during fire fights they were awash with discarded Russian 7.62mmx39mm magazines. Thus the hybrid Knights Armament SR-47 and X47 projects were born, giving SF soldiers what basically amounts to a Kalashnikov but with all the modern Western conveniences of rails and upgraded parts.
The new multi-calibre lower prototype for the SCAR is in this vein, allowing Special Forces (in theory) to quickly change their default SCAR into a weapon which uses a type of round that is most easily found in the theatre where they are deployed. The other good reason for doing this is so they have 'deniablity' – leaving only spent enemy rounds behind after an operation.
Interestingly – from an airsoft point of view – the German developer of this prototype was restricted from using a real steel (RS) SCAR upper receiver in his work due to German gun laws and so had to use that of a ACM airsoft replica!