The RUST SMG Body (not to be confused with Semi Automatic Bodies) falls into the component category of items. These components are used in the creation of multi-tiered items, as well as recycle fodder for players to obtain game building and crafting resources as well as Scrap.
SMG bodies are lootable from an assortment of mid-to-high tier crates, as well as being dropped by some scientist types. They are considerably rarer than their semi-rifle counterparts.
While limited in blueprint viability and scope with SMG bodies only usable in crafting 3 weapons, those 3 weapons make up a weapon category almost all their own. In fact, until RUST players acquire a Workbench Level 3 and the Assault Rifle blueprint, the MP5A4 and Thompson are go-to roaming weapons alongside the SAR… both crafted with this component. This makes SMG bodies viable mainstays in component boxes right up until forced wipe.
With regards to their recycle yield, SMG bodies boast high outputs of scrap and high quality metal. Weapons that they craft are typically the primary ones used in base defense by way of Auto Turret, so make sure that you have plenty in your component box at all times.