16" Suppressed Piston Build Recommendations

[KarlHungus]

EDIT: Ignore the following - I went with a 12.5 upper from Precision Firearms. Hopefully it runs better than the last build...

Hey guys, new to the forum and wanted to get your recommendations for a new 6.5 build. This is not my first foray with the Grendel. I did an 18" a while back, which has given me nothing but trouble. Constant FTF, regardless of ammo. It was built with JP parts, aside from the upper receiver, which JP claims is the cause of the issue. I bring this up because I'd like to use the same manufacturer for barrel, bolt, and upper receiver on this 16" build to avoid (hopefully) those problems.
Since I already have the parts, I'll be pairing it with a carbine length Adams Arms piston system with a .750" gas block diameter. It will typically be run suppressed. Any tips for a reliable build? I'd like something with a larger chamber size so I can reload heavier bullets for hunting, preferably with a cold hammer forged or chrome lined barrel. I'd also like to keep it fairly light. Reliability is paramount. Cost is not a huge issue, but it'd be nice to keep the price for all three parts under $1500. Obviously less expensive is better.

Thanks for any tips you can offer.

[Klem]

Were you using the piston on the build that was giving you trouble?

Why do you want to use a piston instead of a DI Adjustable?

[KarlHungus]

No - that build has a rifle length gas gas system and a JP adjustable gas block. Strangely enough, I have to have it nearly completely open, even when running it suppressed. I know that the block is on there correctly, I sent it in to JP for service and they double checked it. They claimed that they got it running fine by blending the feed ramps on the upper receiver with the cuts in the barrel extension, but I'm still having FTF issues regularly. They never gave me an explanation for why it has to be overgassed to run. Im guessing the gas port is undersized. Also, I measured the chamber OAL and it seems short (something like 2.240 if I recall).

I want to make this gun a piston build simply because I already have the parts for it (piston, bolt carrier, and samson rail with cut out for the railed gas block). If piston builds are a problem with 6.5, I'll switch to a DI.

I just want something that runs. I really like the cartridge. Id also consider something shorter, in the 12.5 or smaller range, since I do have an extra pistol lower. Thanks for the response.

[KarlHungus]

Currently Im looking at the Aetheris ARC15 Tier 2 upper in 12.5". Anyone have experience with these guys recently? I know they have a decent rep in past years, but with the increased demand due to the current craziness, I'm worried that their QC has suffered.
Any other recommendations for sub 16" uppers are welcome. Looking at the prices, I think I'm better off using my piston kit and rail for another build.