Ok with some mods - Armscor Precision Inc Armscor Magazine Fff Vr Series Shotguns 9rd

I bought 5 of these mags and all caused stoppages when new. The bolt carrier hit the top/rear of the mag slowing it down and causing the bolt to not close fully. The follower had too much friction as to effect shell loading. The spring was stacked up on the 9th round causing them to not chamber when full.

FIX: I carefully trimmed down the back / top of the mag where the paint was missing indicating bolt carrier contact.
I cut off one coil of spring at the bottom. Rebending it to grip the magazine bottom plate.
EXTRA: If you cut off 1-3/8" of the magazine base center post, after trimming the spring, 10 shells can be loaded easily and function well.
EXTRA: The feed ramp into the chamber has a square edge and needs gently rounded to feed 100%.
After all of the above operations have been done, mags work well and no malfunctions as long as you use good domestic ammo.