Reliability upgrade - AR10 16" buffer question

I have an AR10 build that I'm having problems with short stroke, the following is my current build:

Aero Precision 16" stainless barrel, it's a midlength gas system (Factory built M5E1 complete upper)
Aero precision non-adjustable .750 gas block
7.25" Buffer tube
Flat spring
PWS h2 308 buffer

went out shooting yesterday and was having reliability problems, the gun wasn't perfectly clean but it wasn't dirty either. I had about 2-3 times where the bolt didn't fully seat, and one major jam with a double feed. Using magpul magazines.

I think I need a heavier buffer, but what do you guys think?