RSCB
I forget what this stands for, I think it's an acronym of people's names. This is the oldest of these magazine systems, and it's core feature is the 90 degree elbow directing air into a T coupler. You then have the barrel on the front of the T, and the magazine behind. You have to tilt your blaster downward to load the next dart. These work well in airguns, but were always somewhat underwhelming on springers.
The oldest reference to it I'm aware of is ShortShit's writeup from 2004. I'm sure whether he is the sole inventor. The popularity of this system has waxed and waned, but it has never really been replaced. There are many, many permutations of this idea using all sorts of different components.
http://nerfhaven.com/mods/ss_rscb/
BRISC
This is an evolution of the RSCB. Uses 45 degree fittings instead of 90 degree fittings, the theory being that it improves airflow. Ice9 developed this in 2009.
http://nerfhaven.com...ng-the-r-s-c-b/
Hopper
This uses a 45 degree wye coupler, so that the magazine is sticking upwards and backwards 45 degrees, and the barrel is in-line with the barrel. Darts load automatically between shots. I developed this system in 2009, originally as an automatic blowgun (demonstrating it's auto-loading capabilities):
https://www.youtube....h?v=DB9b2nvAdJU
Ryan posted one of the original guides for how to mount them to +bows
http://nerfhaven.com...y-hopper-clips/
Chopper
An evolution of the hopper incorporating some of the concepts from the BRISC. A hopper, but with a bent magazine. Streamlines the profile of the blaster, while maintaining automatic loading. Later evolutions of this used a magzine tube that was heated up and bent into shape, rather than using a fitting. Muttonchops developed this in 2010
http://nerfhaven.com...per-with-brisc/
Inline Clips
One system you didn't mention are inline clips (I suppose "inline magazines" would be a better name for these). These have the magazine chamber for darts directly in-line with the barrel, and then the barrel front of that. If tuned correctly, there's just enough air to push one dart through the barrel with every shot. These are typically made by push fitting a barrel of CPVC into a section of PVC tubing about 3 or 4 darts long, and then putting the whole assembly into the front PVC coupler of the blaster. I have no idea where this originated, but I think the concept is a contemporary of RSCB clips.
Edited by Daniel Beaver, 18 May 2021 - 01:06 PM.