My FCP-SR has a really short throat.
The FGMM 175's I have are 2.800 COAL.

When the same SMK 175 is measured to my lands in a dummy case,
The COAL is measured @ 2.795, so the FGMM is jammed .005 on my rifle.

Maybe yours is even shorter, and it's jamming into the lands enough to grab the bullet
upon ejection.

Just a guess...

No idea on the magazine issue, like you said, could be a separate and unrelated problem.