You need to do a function test on the ”Unloaded” rifle/ fire control group.
1. Lock the bolt back, hold the trigger back and hit the bolt release. Did the hammer fall with the carrier slam, or can you release the trigger and pull it again to get the hammer release?
2. Lock the bolt back, hit the release (don’t touch the trigger), did the hammer fall with the carrier slam or can you pull the trigger to get a hammer release after the slam?
3. Cock the rifle, while holding the trigger back, then very, very slowly release the trigger. Did the primary sear catch the hammer, or did the disconnector sear release the hammer, miss the primary sear and the hammer struck the firing pin? A second pull on the trigger should release the hammer.
If the FCG passes all three of these tests (several times), then look at the firing pin/fouled bolt channel causing Slam firings. If it failed during one of above tests, post back which one and we can help you solve the problem.