In the case of his pistol the velocity was set so much higher that even at higher velocity it was blowing the overpressure at the shot.
The easiest way to say it is if liquid co2 gets warm it turns to gas. If it has room to expand, it turns to gas.
So liquid is filling the valve and when he pulls the trigger(opening the gas to escape out the barrel, which drops the pressure) all that liquid turns to gas. A small amount of liquid makes a LOT of gas, so it's overloading the pistol.
Liquid boosts velocity 2 ways. It puts a huge volume of gas into a tiny valve PLUS, the liquid has mass when it hits the tipx bolt and makes that go faster, then hits the ball and makes it go faster yet.
It's normal to have to lower both your overpressure and your velocity adjust a LOT in cold weather.
No help on overlord parts that I know of, sorry!
We play Pistol and we encourage the Few despite the discouragement of the Many.