By the 1890s, the 12 gauge had begun to supplant the 10 gauge as the all-around gauge, and by 1900, the 12 gauge had firmly established itself as the top gauge. By the 1920s, new progressive burning powders allowed for greater shot payloads, and all shotgun gauges improved in performance. The introduction of the semi-automatic shotgun in the 1930s further increased demand for larger gauges. The rise of hunting with dogs brought about the need for larger shells to keep pace with their faster shooting counterparts. Shells over 12 grams were no longer rare, so 20-, 28-, and even 36-gauge shells became common. Today, only 12- and 20-gauge shells are used for hunting game birds like quail and pheasant. Animals like bears and deer are still generally hunted with shotguns containing between 16 and 20 gauge shells. The most common shell sizes for hunting game birds are 6, 8, 10, and 12. Some species (like grouse) are limited to certain shell lengths. For example, only barrels that are not shorter than 48 inches can use 9- or 12-gauge shells. Other animals require different sizes of shells depending on what part of them is being harvested. Hens usually have two eggs per clutch, so they need large shells to protect both eggs. Males tend to fight more aggressively than females, so they need bigger guns too.