TL;DR - Venting frustration after 1300 rounds. The actual gun hasn't malfunctioned, but everything attached has failed. Awaiting service.
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I bought a new upgraded P320 RX full-size 9mm in January 2018. I liked the idea of a modern, factory-produced RDS gun and I shot it well (for me) out of the box on the first range trip. However,
Problem #1: Second trip I noticed the two 17rd magazines it shipped with were extremely tight when fully loaded. It took an unreasonable amount of force to rack the slide over a full magazine, and it didn't feel right. When "topping off" (loading 17+1) and firing Lawman 124gr, the gun did not cycle and the fired casing stuck in the chamber. This was reproducible. Some research revealed SIG branded P320 magazines are manufactured by Checkmate and Mec-Gar, differentiated by the "Made in USA" and "Made in Italy" stamps, respectively. Mine were Checkmate. I bought 4 SIG branded Italy/Mec-Gar magazines locally and this issue disappeared.
Problem #2: The Romeo1 sight was eating CR1632 batteries. Even when completely turned off and with motion activation ("Motac") disabled, the battery drained after 4-5 weeks. This took me a few months to isolate and the Romeo1 is currently with SIG for repair or replacement. It has been 5 weeks as of 2/Aug/2018.
Problem #3: The rear sight falls out. This model shipped with suppressor height tritium sights that co-witness nicely through the Romeo1. I had previously noticed these irons seemed slightly off and now with the Romeo1 in for repairs I decided to zero them. POI crept progressively left until I realized the rear sight was moving and I could pull it out with my fingers. My range's smith reinstalled it but 30 rounds later, the sight was again removable by hand. The slide will ship to SIG tomorrow.
In summary, I am frustrated. I've experienced zero malfunctions with the actual gun itself, but everything attached to it seems to fall apart and/or suffer from serious quality control issues.