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10/6/2025 2:09:18 PM EDT
I was exposed to a FRT equipped 9mm at the range last week, and now I want to play.  I have a Copperhead-K and a MPX-K, both have the upper slot needed for a trip bar.

Friends on another site recommend the Arizona Regulator 3 position for AR use, is that an option for the MPX?  What are my options?  I’m really trying to avoid a science project.

Thanks!
10/6/2025 2:17:54 PM EDT
[Last Edit: jwlaxton][Edited] [#1]
...
10/6/2025 2:27:19 PM EDT
[#2]
Thanks - did you need to do anything to tame the cyclic rate?
10/6/2025 2:35:59 PM EDT
[#3]
The cyclic rate hasn't been a problem with what I tend to shoot.  I'm using an Omega 36M in the short configuration and haven't shot much of the hotter 9mm ammo.
10/11/2025 11:42:35 AM EDT
[Last Edit: heavyduty][Edited] [#4]
An AZR 3P arrived, the widget drops in to my Copperhead-K upper so that’s a good sign.  I went ahead and ordered a PMM trip bar today.

I’ve never had a reason to pull the selector, are AR pattern ones usable?  The ideal would be a SIG three position model, but I’m not finding info on one after a quick search.

I haven’t completely ruled out a Rare Breed for this one, I like the idea of a cassette trigger.
10/11/2025 7:05:19 PM EDT
[#5]
Has anyone tried an Atrius in their MPX?
10/20/2025 3:12:59 PM EDT
[#6]
2021 production Copperhead-K + PMM slide bar + Rare Breed 3P = giggles.  Many, many giggles.

I need to figure out if I can slow this thing down a little.
10/21/2025 2:29:33 PM EDT
[#7]
Quote History
Originally Posted By heavyduty:
I need to figure out if I can slow this thing down a little.
View Quote

https://www.ar15.com/forums/armory/How-can-I-slow-down-the-MPX-ROF-/45-558383/
10/21/2025 2:33:15 PM EDT
[#8]
Thank you, sir!
10/21/2025 3:31:09 PM EDT
[#9]
FWIW I bought a set of the ILWT +20% springs, but I have yet to try them out.  I wanted to have a way to quantify the difference but I need to get a shot timer that calculates ROF.
10/21/2025 4:05:06 PM EDT
[#10]
I was trying to figure out how to determine ROF.
6/7/2026 6:20:02 PM EDT
[#11]
My Copperhead-K with RB 3P was never more than 90% reliable and had horrible trigger slap, so I ended up pulling it out. Last week I dropped in a AZR and finally got to the range today.

I wish I had done this earlier. 200 spicy rounds with absolutely no issues and minimal to no trigger slap, plus it doesn’t feel like it’s on the ragged edge of running.

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