Can birdshot ever be used in a home defense shotgun?

By Jason Wimbiscus

Birdshot refers to some of the smallest shotgun pellets and is often considered inadequate for defense purposes. Playing around with loads did however reveal some surprises.
A well worn topic of debate among firearms enthusiasts is the effectiveness of birdshot for close range personal defense applications. One side will assert that birdshot is for little birds while the other counters that at close range birdshot will create a grievous wound without buckshot’s potential for over-penetration. Curiously, I have found that most of these debates focus the comparison between 00 buckshot loads and light birdshot loads commonly used for hunting dove and quail.
There are many of sizes of birdshot between #9 and BBB and some manufacturers even market shotguns loads stuffed with mid-sized shot for personal defense. (For the purpose of this article, I consider “mid-sized shot” to be any size larger than #2 birdshot and smaller than size 4 buckshot.)  I obtained a sample of such ammo and put it to the test both in terms of terminal performance (gelatin blocks) and pattern.
All rounds were fired into gel blocks at a distance of 15 feet. The close distance was required to make sure as many pellets as possible struck the blocks.

Source: Guns.com