[Will a GEN 3 trigger work in a GEN 5]

Not by itself.  You could possibly change the housing out with a Gen 4 housing and run the Gen 3 trigger bar with the Gen 5 trigger shoe.  They changed the housing between Gen 3, 4, and 5 but I *think* the 4 & 5 are the same size.  The Shoe on the Gen 5 is narrower than the previous gens because of the ambi slide stop (it goes around the trigger shoe now).  So.. maybe with a mix of Gen 3/4/5 parts 

[Apex Tactical's extractor information]

I wouldn't put an extractor in a tumbler. You stand a good chance on rounding the corners and if that happens on the extractor edge you'd have issues with grabbing or slipping off the case edge.

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