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Is this all I need to convert my AR15 5.56 Pistol to a 9mm? — 1 Answer

by Northpole, from FL, United States Asked on May 24, 2022

Name FM Products FM-9 AR 9x19mm Parabellum Rear Charging Upper Receiver, 5 inch w/ Blast Diffuser (3.5)
$349.00 $329.00 Save $20.00
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Answered by Hunter, Gear Expert, from OH, United States, on June 01, 2022

In order to use the FM Products FM-9 AR 9x19mm Parabellum Rear Charging Upper Receiver on an Mil-Spec AR15 lower you will also need a mag well adapter that is compatible with this upper. The manufacturer recommends using the Sylvan magwell adapters with their uppers. The manufacturer also recommends using a heavy buffer and buffer spring.

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Last updated 2025-11-12 UTC.