-It now has a 7 round capacity (there was a 6 round capacity in the D3)
-Improved magazine design (sturdier)
-Magazine can now be used as a suitable handle
-Magazine will not accidently slip out now (area around the mag has been built up slightly to atop this)
-More counterweight rubberbands can now be added without breaking the gun (to prevent accidental fire, and double-fire)
-Improved forward sight (this sight will be pointing perfectly straight, it won't be crooked, or won't fold down)
**NOTE: TO DO THIS INSTRUCTABLE, YOU MUST FIRST BUILD THE D3 Semi-Automatic Handgun from it's instructable: D3 INSTRUCTABLE**
The video is from the D3 Semi-Automatic Handgun, but even though this is the instructable for the D3.1, they fire exactly the same.