I just received my Griffin Armament Optimus and took it out for the first time today. Ran several mags of 5.56 through an SBR and then decided to switch over to 9mm AR pistol. Three lug mount/configured properly. Ran a couple mags of Blazer Brass 124gr suppressed with no issues except a couple where it didn't cycle. Loaded some PPU 158gr subsonics, which I'd never tried before. After one or two, what seemed like a kaboom occurred. Different sound, gas everywhere and mag blown out the bottom but no damage to gun.
Loaded a few more and tried again. Same thing after a couple rounds. Took the suppressor off and went back to Blazer 124 gr. Same thing happened again after 2-3 rounds. Decide I'm done with that gun, and go to put it away. Rack the charging handle a few times and the small piece of brass in the pic below falls out. Found the casings from the kabooms- also pictured below. Trying to figure out what the issue is and hope you guys can help. Questions:
1. This is my first suppressor so first question is what would be the fix for it not cycling with 124gr ammo? Buffer? Spring? Lube?
2. Seeing the bulged cases makes me think firing out of battery. Thoughts?
3. Is it possible that the ripped up casing left a piece of brass in the chamber or stuck between bolt carrier and upper and was preventing either the round from fully chambering or bolt heading all the way home this causing OOB firing?
4. This is a pistol with a blade brace and I was cheek welding it, not shouldering it. Is that like limp wristing a pistol an causing issues?
5. What would your next steps be? I want to get some opinions before I fire it again.
ETA - pieces of the follower got broken off during all of this. See the mag in the pic.
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