Break action? If so they are pretty good. The good ones use the same type of piston that holds your rear hatch or hood open. The only thing is over time they get wiggly and they lose accuracy, wear on the hinge. Any trigger time is good trigger time.
I don't know about the Gamo Swarm specifically but generally speaking magnum break barrel air rifles are extremely hard to get consistent good accuracy from. Like Sawman said above learn the correct way to shoot a springer. If you've not learned it before google "artillery hold", read it and practice it, thousands of times...
Also they are usually very picky about what pellets they like. Go to somewhere like Pyramyd Air and get a pellet sampler pack, or several sampler packs from different brands (JSB, H&N, Air Arms etc.) you may have to try different pellet weights and head sizes to find what your gun likes. Magnums will usually like the heavier pellets to slow them down. Pellets do funky things in flight when they start getting too close to the speed of sound.
When starting out don't be surprised if your group sizes are measured in inches rather than fractions of inches. After much practice and finding the right pellets for your barrel shooting a springer can be fairly accurate and give a feeling of accomplishment when you can get a nice tight group or take out small game at a decent distance with 1 well placed shot.
That is partially why for squirrel control I just use .22 rimfire quiet loads. It is my understanding that target grade spring guns while costly are must more accurate. I was not familiar with special holds, but it makes a load of sense since it has a very long 'ignition time'.