We all know that GBB stands for gas blowback and NBB stands for non-blowback. And we all know that the difference between these two types of gas airsoft pistols is whether the top slide moves back and forth or not while you fire. But is that really it? What is the effect of either system on the gun and the user? This article explores the differences no one talks about.
Most folks talk about gas guns as the holy grail to simulating real firearm recoil. But most folks doesn't make it explicitly clear that it is not necessarily the gas that makes the airsoft gun recoil, after all, an airsoft electric gun uses "gas", too. It is the back and forth motion of the moving slide that simulates recoil.
That becomes very clear when you try two of the same gun, one GBB and one NBB. You'll see that the GBB pistol has much more recoil than the NBB pistol.
GBB is more realistic than NBB, because the physical slide motion is similar to the real gun. The sound of the sliding slamming back and forth also improves the realism. If you are making a movie, you will want the simulated slide movement, unless you are making a science fiction movie.
One obvious difference with a moving slide and a non-moving slide is the number of moving parts. Because NBB's slide does not move, and assuming everything else is equal, a NBB gun is inherently more solid and more robust than a GBB gun.
Moving parts means energy is needed to move those parts. A NBB has no moving parts, so gas is only needed to expel the BB. A GBB needs gas to expel the BB and to move the slide back. Therefore, on the same airsoft gun that are available in both GBB and NBB versions, the GBB version will use more gas.