I'm sure this topic has been beat to death but almost everywhere(forums,youtube,reddit, FB groups) are giving info that sounds compelling but then I read other things out there on the web and well I dont know what to do at this point. Before I get beat down here lol, yes I know parts compatibility and "mil-spec" is non-existant in the LR308 world. Here is the parts list:

18" SOLGW Rifle barrel
Lantac BCG
A5 tube
Sprinco green rifle spring
h3 3.25'' buffer

BCG is hitting the buffer tube and not sure what the fix will be? Putting 2 quarters down the tube? Filing down the buffer tube? Switching over to a carbine tube with a sprinco orange carbine spring?

I dont want an adjustable gas block as SOLGW preaches not to run one and I run mostly suppressed all the time. I've been told that you need to run a 308 spring in the a5 tube instead of the green sprinco spring so I have a JP large frame rifle buffer spring on order. I have tried running it with my cheap PSA BCG and still getting malfunctions.

I would like to fix this the most economical way at this point. Whats the solution?

TIA!

The carrier key is hitting the front of the buffer tube?  

No. Hitting both bottom sides of buffer tube.

When you push the bolt carrier back manually does it bottom out?
I am wondering if you need an A5 buffer instead.

it does not bottom out. I used the A5 buffer when I initally got the system and found out the hard way that the a5 buffer is too long. Was not getting bolt lockup on last round.

It has barely started to touch the threads and I'm afraid at removing the buffer for fear of causing more damage to the lower receiver.

I am running the Aero H3 buffer. Understood on the green spring. I have a JP large frame rifle spring on order. Hopefully that'll do..

Proper spring would help but could also can introduce ejection issues.

The AGB would be my recommendation regardless. I don't get why the barrel manufacturer cares what kind of GB you use anyway unless they have a particular GB in mind that always works perfect with their barrels no matter what ammo or anything else you are running.

Listen to Bfoosh.  They helped me with my BCG buffer bashing 308 woes

Sounds like you are running the correct buffer length, you need a stronger recoil spring.  

I ran into buffer tube bashing with a5 length buffer + AR 308 short buffer.  For me a spacer fixed it.  You are running the correct length buffer-a carbine buffer.  An a5 length buffer would only work for a 556 in this instance.  308 needs a little more length to travel

Get a rifle length ar308 spring- sprinco orange or tubb should work

Use a tubbs 308 flatwire spring.  I think the buffer is correct but the spring is so light that the rubber is compressing to the point the bcg travels an extra 5mm and touches the lower.

I've been confused since the OP.  Would love to see pics as well.

sounds like you're getting too much force on that buffer bumper, compressing it completely like play-dough.  stiffer spring should remedy that, or adj gas block.

FWIW, PSA "AR-10" lower: