r/supersafety

Recently picked up a BRN-4 10.4 upper and shot it with an ARC Fire recently. Previous owner drilled gas port to 1.9mm and with the Griffin HRT5K, H3 buffer and carbine spring , ROF seems pretty high (I got 950 using an online calculator, maybe u/Next-Conversation234 can help me with that).

I’m thinking of picking up a new chrome lined 10.4 barrel from Brownells, but I’ve heard the factory gas port is pretty small. Can someone recommend what I need to drill to run the FRT successfully with a low backpressure can to get to around the 750-800 RPM mark?

Apologies for upside down video. So finally printed off some cf yeet sheets for my alloy and for the most part they work. However, semi does not work at all unless i slowly close the bolt. And im at my whits end with it tbh because I cannot thing of a single thing that would make semi not work 100% especially given that I put said cut trigger in other firearms and it works fine.