How to make a Glock 19 from Polymer 80%

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@Silverback manufacturer FFL completes his Polymer80 80% lower and assembled into a working Glock19. https://www.youtube.com/watch?v=ThzFOIYZgIg&lc=z23xudu5lx33htnfmacdp43a02eyv5cvrka0vat3enhw03c010c.1566226869875000