Can low air cause fps variation in a hpa rifle

I was testing a new chrono I got and I was getting readings around 1.63 joules then randomly a few shots would go down to around 1.55 or up to 1.68 could these variations be caused by low air in my tank I’m at around 300 psi left in the tank. I also just installed a new 4uad bucking so that might be causing it aswell