A typical Semi - Auto trigger group. 3 of the parts are included in the US part count

Typical Single Hook AK47 Semi Auto Trigger Group

Many of these US made kits do NOT include the spring, so keep that from your parts kit


Hammer

Hammers are pretty much all the same, some look a bit different, The full auto hammer has a little different shape

One of the parts on the 922(r) Compliant US parts count list

Hammer Spring

Double coiled spring designed to work even if one coil snaps


Sear

The part that holds the hammer back until you pull the trigger

One of the parts on the 922(r) Compliant US parts count list


Single Hook AK47 Trigger

Trigger with one arm that grab the hammer.

One of the parts on the 922(r) Compliant US parts count list