I agree; it’s puzzling.
If ammunition is fed, then the bcg is moving far enough rearward to force the hammer to hook the disconnector. And I’m sorry I asked if it stripped a round. I see that you addressed that in the first post.
Here’s an animation of how the standard semiautomatic AR15 trigger works. You can see the disconnector in purple.
https://youtu.be/xh2FjzVVIZY
The Geissele SSA moves the sear but the function of the disconnector remains the same. A bad disconnector spring could cause the problem you’re having, but I don’t see how that would be ammunition sensitive. Broken, misaligned , or worn engagement surfaces on the disconnector and hammer could also cause a similar problem.
I’m sorry; without actually looking at it I don’t know. I would have it open looking at all the engagement surfaces.
I would really recommend calling Geissele to see what they say.
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