Around the time of the Civil War many private gun makers were experimenting with breech-loading rifles. Some continued to use paper cartridges; others used metallic. The secret was to build a breech mechanism that could withstand and contain the explosion of the gun powder. For the safety of the soldier, and to get the most efficiency out of the cartridge, the breech had to be sealed tightly to prevent the escape of gases, yet the weapon had to be capable of being reloaded quickly and not jamming. After the War, Springfield undertook production of some of these weapons in addition to their Trapdoor models.