At DESY we follow a superconducting RF (SRF) gun cavity design with a cathode plug screwed in a clean room into a hole at the cavity backside and sealed with indium. This improves the cathode cooling and supports keeping the cavities clean. In contrast to setups with cathode insertion systems, exchanging cathodes requires a complete disassembly of the cryostat and bringing the gun cavity back into the clean room.