Other Is STD deviation temperature related?

[Patrick1]

I’ve recently been doing some testing on my Maverick. Basically, at low temps, I notice higher std deviations and “extreme spread” increases than when temps are higher. Trying to let you folks comment on why this may be happening. At higher temps I can get 1-3 fps std deviation and 6-7 ext spread.
At low temps, I get 6-8fps std deviations and 15-18 fps ext spread.
Also, I noticed if I bring the cold gun inside, after seeing high ext spread and std deviations, that as the gun “warms” the std deviations and extreme spreads improve.
Sooooo, your thoughts and explanations?
Anyone else notice this?

 

[Kgphotos]

Temperature changes can have an effect on your air pressure in your tank and in your plenum. Temp changes can also effect the metals in your rifle. The hammer may glide smoother when warmer than when cold. Especially if it has any lube on it. These variables will influence your standard deviations and extreme spreads.
Kenny

 

[HogKiller]

I don't have an issue with mine. I only use very light Mobile 1 on my guns, it if moves it get M1. I made sure to lube the hammer, falls in the moves category. You can also spray a little Tri-Flow in there, that'll work wonders.

 

[AirNGasman]

Like Co2 guns, but to much less obvious 'degrees' (pun intended), PCPs will chill when shot at relatively fast cadence. That becomes much more exaggerated and obvious in cold temps. And with several parts involved in the firing mechanism, most metal, shrinking and expanding with the temperature, so do velocity consistencies.

 

[nervoustrig]

For guns used in cold conditions, go with a dry film lubricant on the hammer (tungsten disulfide, molybdenum disulfide, or graphite).

 

[stovepipe]

I’ve recently been doing some testing on my Maverick. Basically, at low temps, I notice higher std deviations and “extreme spread” increases than when temps are higher. Trying to let you folks comment on why this may be happening. At higher temps I can get 1-3 fps std deviation and 6-7 ext spread.
At low temps, I get 6-8fps std deviations and 15-18 fps ext spread.
Also, I noticed if I bring the cold gun inside, after seeing high ext spread and std deviations, that as the gun “warms” the std deviations and extreme spreads improve.
Sooooo, your thoughts and explanations?
Anyone else notice this?

Hi Patrick1. I notice that you have not mentioned anything about changes in plenum pressure. Are we to assume that the plenum pressure is the same for every shot you take? What are your observations about plenum pressure in warm vs cold temps? Without knowing this, observations about muzzle velocity are not of much use.

Here is a real example of what I'm talking about. Not long ago I dropped my reg pressure down from 161 bar to 149 bar. I never did finish adjusting my hammer to find the max muzzle velocity because it started raining on my chrony, so I called it quits for the day. A week later I went out in the cold (low 30's F) to finish finding my max velocity. I look at my plenum pressure before the first shot -- 149 bar. I take the shot -- the plenum pressure climbs to 156 bar. And the plenum pressure climbed to 156 bar for the other 12 shots I took. I take my mav back in the house, wondering what the hell is going on. A few minutes later I dry-fire the rifle a few times in the house -- after each shot the plenum pressure climbs to 149 bar and stays there. Since I want to tune the mav for 149 bar, none of the muzzle velocity readings I got outside mattered at all -- that is completely useless data since the plenum pressure was not where I set the reg to. In my case, the regulator is obviously not doing it's job well enough, so there's no point in me considering how other parts of the rifle are affected by cold temperatures until I rebuild the reg and get it working well.

Sorry if it sounds like I'm picking on you. That's definitely not my intention. I'm just curious about the plenum pressure changes in your mav more than muzzle velocities.

stovepipe

 

[stovepipe]

After my last post, I started wondering if my pressure gauge is giving me a different reading in warm vs cold temps. It's a wika 28mm 0-250 bar gauge for the plenum pressure. Hmmm... Thinking... I don't know.

stovepipe