DDM4 rifles are available in three main calibers: 5.56mm NATO, . 300 AAC Blackout, and 6.8mm SPC. While there are pros and cons for each of these calibers, and reasons you may be attracted to one over the other, the majority of DDM4 rifles are chambered in 5.56mm.
https://danieldefense.com/wire/fir...
— LiberalForum Archive