When all else fails, Bark like a dog !
Mossbergs fix seems to be selling the rifle in the lss chassis now, it's magwell has significantly less slop.
Modular Driven Technologies Corp (MDT)
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Unfortunately the aluminum mag well from Tromix isn’t available in Canada. Have tried and they won’t ship it. There is also a fairly easy fix with leaving the magazine a little on the sloppy side. Using a die grinder or a Dremel, change the feeding ramp surface by machining out a bit more of a degree to accomadate the mag in the backward position. Remove only a little bit of material at a time. Reassemble check feed, then take it back apart and remove more if needed. Mine now works like a charm.