Quoted:
For understanding purposes as far as lower receiver components are concerned, is the Geissele SSF itself a full auto trigger group that with the addition of a selector switch would make an M16 full auto capable? Does the SSF contain an auto sear in its assembly or is that still a required component that is missing from previous statement?
If an auto sear is still required to make the SSF trigger function on full auto, why makes it different than their other products.
Educate me.
"Educate me."? Boy, that's a dangerous request here ....
OK, let's start at the beginning: Eugene Stoner designed the AR15 as a select-fire rifle. Each of the five parts in the fire-control system –– hammer, trigger, disconnector, selector and autosear –– is designed to play a role, allowing the gun to fire in either semi-auto or full-auto.
There are some good comparisons elsewhere on ar15.com of semi vs. FA parts, with photos and specific descriptions. I'll let you search for them yourself among the tacked threads. There are also some good animations out there that show how the parts interact when firing.
After a few years, Colt –– which had purchased the AR15 patent from Armalite –– decided to come out with a semiautomatic version. So they redesigned each of four of the five parts (hammer, trigger, disconnector, selector) so that they would function in semi only, and they discarded the fifth part (the autosear, which for the most part governs the timing of full-auto fire) because it was not required on a semiautomatic firearm. Thus we have the neutered AR15. I prefer to think of it as an original AR15 design which has had its testicles removed, but that's just me.
The SSF replaces only the trigger and disconnector of the host gun. It still requires a milspec full-auto hammer, full-auto selector and an autosear to function correctly and safely. It does make a full-auto AR function much more smoothly, but it is far from the complete fire-control system required for full-auto function.
HTH.