PA10 Problems . . .Help?

[MolonLabeCalif]

I'm new to this forum, so please be gentle. Didn't know where else to turn for ideas/advice. Right up front, I apologize for the long post.
I bought a complete PSA PA10 SS18” upper w/standard BCG and mid-length gas system w/standard gas block. Ok, before you criticize me. . .I chose to try out a polymer lower (80% WarHogg). I'm not sure I like it, but that's what I have for now. I’ve only tried Magpul Gen 3 mags with it. The issues I’m having don’t “appear” to be lower-related. This isn’t my first build, but is my first that hasn’t functioned properly. I’m fresh out of ideas.
All test firing has resulted in failures to feed, failure to pick up next round, inconsistent/erratic ejection angle and failure to lock open on last round. I’ve tried 3 brands and grain weights of ammo, from 147 to 168.
So, this is what I’ve done: I started with an enhanced power buffer spring and standard 308 carbine buffer (3.25oz); Changed it to a standard spring; tried a heavy buffer (5.25oz); inspected the gas block for proper position; Installed an adjustable gas block; disassembled/inspected the bolt, etc. The last test I performed was firing one round, with mag removed, manually holding the bolt latch to simulate an empty mag…it failed to lock open. However, it DOES lock open when manually opening the bolt with an empty mag installed, so I know the lock works.
I’m really leaning towards it being an under-gassed issue, so I researched gas lengths and gas port sizes. I didn’t find data for an 18” specifically - what I found indicates a 16”/.750 barrel should have a port sized from .070-.086, and 20”/.750 should be .093-.096. My gas port is only .073 – definitely on the very low end of the spectrum.
Other things in question . . . I read that an ejector with too much spring force can play into functioning issues. The info said I should be able press the ejector in with only my finger. It suggested changing the spring if it required using a tool to depress it in the bolt. Mine is extremely strong, even using a tool.
The magazine does seem to sit a little higher than I’d like – the bolt slides more freely without a mag installed than with an empty one in. I can feel slight resistance when slowly racking the bolt open & closed. However, I don’t think it’s enough to slow the bolt when recoiling … but, you never know.
What’s the general consensus on this? Any other constructive ideas? I hope someone can help me out.
Thanks!

[PrarieDog]

my guess would be that it is under gassed. As you have an adj. gas block you could open up the hole slightly and be able to back it down later if it proves to be under gassed. Don't know about the lower if that is causing issues with the magazine not positioned properly (too high causing drag on the bolt) but I do not trust the poly lowers. Easy try with opening up the port. Shit can the lower though.

[MolonLabeCalif]

Thanks. Ya, that's all I could think it is. As for the lower / yes, I'm not impressed with it. But it was an inexpensive 80%er to try. It sure milled easy. I'll enlarge the gas port, then I'm going to order a billet lower, while I still can (in this pansy-ass, bleeding-heart, liberal state.)

[Iraqgunz]

Here's a good consensus. Before you spend more money fixing what was essentially a new upper, contact Palmetto State Armory and make them address the issue. My gut intuition tells me that you lower isn't the issue. After you have done that, let us know what happens.