Al in Mi wrote:might want to bump that load up to about 3gr, 38-39gr seems to be a sweet spot for most guys plus it will get you some extra gas.
What he said!
If using lighter loads exacerbates the problem, that really points toward your original assertion regarding gas volume. And that having been said, using reloads to troubleshoot a cycling problem, introduces another variable to the equation. Not that your weapon should limit you to only using factory ammo, but lets face it, reloads, even using best engineering practices, are a variable. However, if you want to take the test to its ultimate conclusion and I don't mean that in a destructive way, try some loads that are hotter than factory and see if the pendulum swings the other way. You can exceed the "lawyer approved" factory loads without stepping into dangerous territory. Go a little over the line, don't floor it. My experience with my AR 450b is that the current blend of Lil Gun pushing 250gr FTX, hits factory rated velocity at 37gr. I have also shot 38gr loads and though they exceeded factory ammo velocity, they didn't exhibit excessive case head growth (best pressure metric). A properly tuned 450b AR will be very forgiving of ammo choice with regard to cycling reliability. I know. I have experimented with countless combinations of bullets and powders over the years.
Hoot