Taken directly from Nodak Spud website. This is the issue they are referring to in your post:
"There have been reports that the Tapco G2 "single hook" fire control set has had malfunctions when installed in some receivers on the market. These reported malfunctions have included the NDS-3 and the old model NDS-65 "economy" receivers.
The most common problem is "hammer follow".
This is when the hammer is NOT caught by the disconnector, and follows the bolt carrier forward, failing to reset for the next shot.
This does not occur in all builds involving our NDS-3/NDS-65 and the G2 "single hook" set.
But, we advise that caution needs to be observed when combining these two products.
Hammer follow is due to a combination of small dimensional variances on each of the parts in the assembly (called "stacking dimensions").
When you combine them together, the hammer is not pushed down far enough for the disconnector to grab it.
The parts generally involved are; bolt carrier,receiver, fire control group"