If any of these worked, you could easily have a magazine tube running on the top like a shotgun where the bullets are held and a magazine containing an energy source so that you could reload either.
I imagine a laser could easily be considered a destructive device. A typical bullet fired by magnetism? Not so sure.
Some of you no doubt know how an explosively formed projectile works. Fire a copper plate at very high speed and it forms itself into a kinetic projectile.
A SF writer named David Drake does a lot of future combat writing and he used weapons that functioned similar to a railgun but excellerated a disk at high velocities that behaved like an EFP. The disks made easy storage in long tubular magazines. From Infantry weapons to Tank Cannons they all used the same technology similar to the way our current weapons do.
Colt M1911, AR-15 | S&W Model 19, Model 27| SIG P238 | Berreta 85B Cheetah | Ruger Blackhawk .357MAG, Bearcat "Shopkeeper" .22LR| Remington Marine Magnum SP 12GA., Model 700 SPS .223