Ok I’m trying to build an AR-10 in a 6.5 Creedmoor. And so far I have the fallowing parts and need a little help trying to find the last piece.
Geisele trigger, non-rotating pin set, PRS stock, Gunfighter charging handle, AR-Restor buffer, Pistol Grip,  
I have a DPMS lower but I’m going to save it for a another day and I’m going to order a MEGA MATEN .308 upper/lower
I just ordered my Krieger Barrel and lower parts kit but I’m having a hard time finding a good gas piston kit. I can’t wait until I get off this deployment so I can put it together.

No one makes a "kit" for the 308 AR. As of SHOT show this year, alot of the piston makers, Osprey, Adams, etc have all backed off making the 308 kits. Instead, they are moving towards complete uppers instead.

My advice is to use the standard DI system, especially for a 6.5 Creedmoor.  Op-rod operating system in the AR platform just make things more expensive, less reliable, and less accurate.  They are one of the most successful marketing hype strategies pulled over on gun owners in the past 10 years.

The proof is in the pudding, because designers who have been instrumental in some of the more recent op-rod designs don't even use them in their high-volume training courses.

HK416 and Magpul Masada/ACR, just for example.

The consensus for precision guns is to definitely use a DI gun in the AR10 platform.  I can only imagine the problems an op-rod design would introduce with the Creedmoor.  What gas port diameter would be used?  What buffer?  What bolt carrier?  What recoil spring strength?  What barrel diameter would be used to counter the weight and inconsistencies introduced by the gas block, op-rod, and other recoiling parts that are no win-contact with the barrel?

$11 gas tube, $25-$70 gas block and your standard AR10 BCG are all that are needed for proven, reliable, accurate performance.  When I see companies who have been pimping op-rod driven AR's start to offer drop-in DI conversion kits for them, that says a lot.

or you could, you know, answer the question he asked.  

The question I see is:
"AR Gas piston?"

My answer is "don't do it".

Friends don't let friends install gas pistons in their AR10's, unless it's the DI bolt.

He did. "I wouldn't do that if I were you." is an answer. He gave his reasoning behind the answer, as well.

DI all the way, pure physics and nothing more is required. A logical and proven design that is both efficient and proven reliable. Listen to the Pros.