Second regulator Impact M3, 10-12 bar higher after shooting session

[TonvanderLinden]

Hello,

My M3's second reg tends to be around 10-12 bar higher than the set pressure, everytime I come home after shooting my gun at the range. (outdoors temp difference with my house: 22 degrees (fahrenheit) After dry firing a few shots it returns to normal. Is this normal??

Sincere greetings,

Ton van der Linden (Netherlands)

 

[TDK]

When you leave the range, you have cold dense air trapped in your plenum at the set pressure of your regulator. When you bring the gun inside, the air inside the plenum warms up, and since it has nowhere to go, you'll see a pressure increase in the plenum until the next time the gun is fired. There is a multiplier to this effect - and that is the fact that the plastic reg piston shrinks in the cold which shifts the reg set point higher. So your reg set point will be higher in the cold and cold air at that higher pressure is trapped in the plenum when you head home and take it inside.

Seeing a +10bar increase when moving from cold to warm environment like this is pretty typical, although I think I see that more with a temperature differential of around ~35deg F

 

[TonvanderLinden]

When you leave the range, you have cold dense air trapped in your plenum at the set pressure of your regulator. When you bring the gun inside, the air inside the plenum warms up, and since it has nowhere to go, you'll see a pressure increase in the plenum until the next time the gun is fired. There is a multiplier to this effect - and that is the fact that the plastic reg piston shrinks in the cold which shifts the reg set point higher. So your reg set point will be higher in the cold and cold air at that higher pressure is trapped in the plenum when you head home and take it inside.

Seeing a +10bar increase when moving from cold to warm environment like this is pretty typical, although I think I see that more with a temperature differential of around ~35deg F

Thank you so much for answering my question.

 

[TonvanderLinden]

I went out to the range again yesterday, and kept a close eye on the second reg during shooting. I shot around 150 shots and saw the 2nd regulator pressure rise up as time went by. It started out at 142bar and at the end of the session it was at 148bar. So, I'm guessing there's more at play than just the temperature differences.

Two more things;
1. My first reg creeps up 10-15 bar during shooting, but I thought this was acceptable, since there's a second reg backing it up.
2. I had my second reg replaced by a Huma reg a few weeks ago. The original (FX) 2nd reg had the same problem.

What's going on here? Am I nitpicking here and should I stop being so obsessive over the numbers or is there really something wrong?

My setup is as follows:

Impact M3 Sniper .25, Slug power kit installed with tungsten hammer\weaker valve return spring(left the rubber ball out)\pinprobe, Manometer second reg is a Sekhmet.

Sincere greetings,

Ton van der Linden