Temperature inside/outside pellet velocity change
- Thread starter ladwict
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Don't fight it, go with the flow. Instead of battling to try and keep the gun warm, just know how your gun shoots at different temperatures like others have suggested. Add hammer adjustment clicks or scope clicks to compensate. My M3 has significant reg set point shift with temperature change. There may be some non-reg temperature caused speed effects as well, but in the end everything is all rolled together in the speed seen leaving the barrel. I chrono'd the gun at various temperatures and know exactly how many hammer clicks I need to add to get back to my 70deg speed setting.
You mentioned pellets, which makes me wonder which is affected more in this area: pellets vs slugs, and large vs small calibers
You mentioned pellets, which makes me wonder which is affected more in this area: pellets vs slugs, and large vs small calibers
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Thanks I will “go with the flow” but that is why I am just finding out what that flow is …..
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Hello Gents, yes, I also wonder why you are lubricating a spring at all? Maybe at the ends where they contact other parts so nothing binds, but other than that I can't see what advantage this is. Even for that, A dry lube would be better to avoid dirt buildup sticking to the lube. I use a little graphite, (pencil lead), for this. Unless parts are rubbing against each other oil, or whatever lube should have no effect on spring performance.
To Ladwict, do you know what the pressure is at 70 degrees? Going from 70 deg. fill to 32 deg. shooting outside, you should see a change in pressure. Can you do that test? I honestly believe this is the culprit for FPS drop, especially for metal tanks. Aluminium will change temp to ambient very quickly, steel only slightly longer. You could probably heat the air quickly with a hot wet towel wrapped around tank and see if FPS goes up. Electric sock would help I believe.
To Ladwict, do you know what the pressure is at 70 degrees? Going from 70 deg. fill to 32 deg. shooting outside, you should see a change in pressure. Can you do that test? I honestly believe this is the culprit for FPS drop, especially for metal tanks. Aluminium will change temp to ambient very quickly, steel only slightly longer. You could probably heat the air quickly with a hot wet towel wrapped around tank and see if FPS goes up. Electric sock would help I believe.
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The reg is set at 135 bar. Taking the gun from warm to cold makes the reg gauge drop approx 5 bar to 130 bar. From then on when I have fired the first shot in the cold the reg fills up nicely again to 135 but the speed remains lower then with 135 bar inside shooting at warmer temp.
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Have you let the gun sit in a cold environment, like a garage, for an extended period of time (many hours) and then done testing? The first hour or so after environment change is going to be when things are constantly changing as the gun cools down and equalizes with surroundings.
I left my gun in the garage overnight before I did my testing. Now when I am going shooting, I put the gun out there early so it can get fully cooled down, rather than pull it out of a warm case right before I shoot.
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This is interesting. I wonder in dropping temperature effect spring rate? If a colder spring doesn't rebound as fast when it's colder it could impact the speed. Just a thought.
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I don't think the temp range you are dealing with would produce measurable changes in spring expansion rate. That would mean the spring would change with cocking and firing several shots because it warms with movement, which would affect FPS. Range to narrow.
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Did I mention pellets? I shoot Slugs 41gr Griffen HP CB they are the best Slugs out of my impact mkII PP under 1" @ 100 groups however most beaver shots are under 25 yards as it's dark and swampy most of the time.
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Cold air flows slower than the hot air as the particles have less energy. The reg pressure may be the same but the particles excitation is lower in cold temp. I believe that is the most significant factor influencing the v0.
Out of all the replies, I feel this is the one I was looking for. If the only thing that changes is tempature I totally understand cold air is less excited shall we say. Physics always has the answer! I should have stayed in school longer
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Same thing occurs with my TX200 Springer…. As the temps get colder, the air is denser which in turn creates more drag on the pellet. .5 mil at 50 yards is consistent if there is a 20° shift…. It was 60° yesterday and 40° this morning and my gun always is always bout .2 mil low at 50 yards…. I just use the reticle to compensate
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Interesting.....
Would it be a constant? : The lower the temperature the lower the fps?
Or would it be a just one hit : Close to frezzing you loose X fps?
Would it be a constant? : The lower the temperature the lower the fps?
Or would it be a just one hit : Close to frezzing you loose X fps?
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Cold air is more dense than warm air. Put the numbers in Chairgun and you will see what's going on
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Where I live the average temperature is 63 thats what I make my dope card at. For every 25 degrees difference I add or subtract .1 mil
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HAHAHA as i read this . Aluminium will change temp to ambient very quickly, steel only slightly longer. You could probably heat the air quickly with a hot wet towel wrapped around tank and see if FPS goes up. Electric sock would help I believe.
i pictures all you hunters with a battery sock on your air supply walking through the woods
Really liked this posting , as i will be shooting in the colder outside weather , and now realize FT matches in the cold months would be a challenge other than freezing one's butt .
i pictures all you hunters with a battery sock on your air supply walking through the woods
Really liked this posting , as i will be shooting in the colder outside weather , and now realize FT matches in the cold months would be a challenge other than freezing one's butt .
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That brings up a good point….. ever since the weather has been so random with it being 60° one day and 40° especially between night and day, I feel like I’ve had zero’ing issues on my Hawke Airmax 4-12x AO and wonder if it’s my cheap UTG Leapers aluminum rings…. I wonder if getting a better mount would help
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i could use an electric sock lol ... temp affects everything though, from projectile drag in the bore, to oa pressure, to oring performance .. dont fight it .. just roll with it lol ..
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maybe we should buy electric sock stocks ? I already have a mod to use " cut a hole in the toe of sock, slide the sock over the barrel and air supply connect wires to battery pack on belt . Happy hunting !"
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I agree with this. Density has more effect than any other variable in this situation. Like flying a plane. We are flying pellets. Despite all variables with the gun, the projectile will still be flying thru denser air when its cold.
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