My first AR: 7.62x39 with Superlative Piston kit - Learning from failure...

[Pressingonward]

UPDATE: learned from my failure and abandoned the piston system in favor of DI for this rifle as you can read about in later posts.

Hello everyone,

This is my first post to this forum - I've been lurking for a few weeks now and have learned a lot - thank you to everyone for the knowledge you've shared! I - being an idiot - decided to wait until this year to buy my first gun (a Ruger EC9S) and get my concealed carry permit. I did some shooting growing up, but as an adult never got around to spending the $$ to get into shooting until now. The current societal conditions have finally convinced me that being able to defend myself and my household are a necessary investment...plus I love shooting

All of which leads me to my AR build. I wanted a general-purpose sort of rifle for home defense/SHTF/plinking, so I started doing research and quickly landed on the AR as the obvious choice. After looking at the various caliber options I settled on 7.62x39 as the only reasonable option - it's the only caliber that I can find ammo for at a price that won't bankrupt me - if the insanity ever dies down I'll eventually build up a .223 AR, but since I can't buy ammo for one right now there isn't much point in building an unusable gun...

Anyways, here's a quick summary of my build:

• Aero Precision M4E1 (not enhanced) upper and complete lower
• Dez Arms 7.62x39 barrel: 18", mid-length gas, fluted HBAR
• Superlative Arms Piston kit
• Faxon 7.62x39 bolt with mil-spec firing pin per Faxon's recommendation
• UTG Pro M-LOK 10" handguard
• Radian Raptor ambi charging handle
• Mil Surplus carry handle
• Generic clamp-on gas block for a front sight base
• UTG fixed front sight

Here's a couple pictures and then I'll get on to the "failure" part of this build and ask a couple questions that I'm hoping you all can help me with.

IMG_20201022_070923134 (Large).jpg

IMG_20201022_071016135 (Large).jpg

You might notice in the first pic that there's no front sight...I wasn't paying attention when I ordered the FSB and ended up with a rail-height FSB and a gas block-height front sight. Was also disappointed to see that unlike the US-made UTG handguard, the UTG front sight is made in China. I think I'm going to go with a Daniel Defense front sight to replace the too-tall UTG. For my first test firing, I didn't want to wait, so I made one

IMG_20201022_135119696 (Large).jpg

IMG_20201022_135130338 (Large).jpg

As bailing-wire-and-bubble-gum as it is (I spent a whole 15 minutes on it...), the makeshift front sight worked great, and my first shot (at about 10 yards) was dead center horizontally and about 2" low - good enough for now.

The minor sight SNAFU notwithstanding, the real issue with this build is my combination of caliber, barrel, and piston kit - it doesn't work. I didn't realize until recently (being a noob...) that the 7.62x39 cartridge produces lower gas pressure than the .223/5.56. I should have contacted Superlative Arms to get their input before ordering a barrel - I now know they recommend a pistol-length gas system for all 7.62x39 builds whereas my barrel is mid-length. I specifically bought this barrel because I wanted the mid-length gas system after reading about how great it is on a bunch of different websites - not realizing that this was specific to the .223/5.56 caliber. My gun will only half-cycle the bolt after each shot - it's way undergassed.

I've seen a blog online where someone has had success using the Superlative Arms piston kit on a 7.62x39 gun with a 16" carbine-length gas barrel, but that's the only reference build I've been able to find online. My initial hope was that I could open up the gas port on my barrel and solve the issue by increasing flow, but I pulled the piston gas block off and my gas port is 0.125", which is considerably larger than the gas port in the Superlative gas block.

Here are the possible solutions that I see moving forward:

1. Enlarge the gas port on the piston kit gas block to increase flow to the piston. Try a lightweight buffer spring.
2. Buy a new barrel
3. Buy a traditional DI gas block, tube, and bolt carrier (give up on the piston kit for this rifle)

I'm leaning towards option #1 because it's the quickest, easiest, and cheapest option. If it doesn't work I've potentially trashed a spendy part of the piston system, but I figure if I drill it out and still can't get proper actuation with my current barrel, the gas block would probably work OK with a carbine length gas barrel. It's all speculation at this point though...

Options 2 and 3 are difficult as I've spent my budget and don't really have the money for them. I could sell my current parts and make it work, but that'll take a bit of time. For option 2 I haven't been able to find an off-the-shelf 16"+ barrel option with pistol-length gas (don't want to make it an SBR). I could get a custom barrel for $250+ with pistol length gas (my preferred option if I had cash to burn - what I should have done had I known at the start of this build), or get a carbine-length gas barrel for $100-$150 and try to make that work (I suspect it would).

Any and all input and advice would be appreciated - don't want to ruin my piston kit gas block if that's not going to be a path to success...