I have a co2 rifle when i change a co2 cartidge, i always have to zero the scope, but i dont know why. Anybody have any idea?
Co2 accuracy problems
- Thread starter CiklaMan
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I think it is because new one have higher presure like on pcps if you go to low or too high poi changes.
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^^^ that
...but it also brings up another question. If you re-zero when changing the CO2, do you also re-zero as that CO2 is used up? The rifle should regulate the CO2 for consistency from shot to shot.
I have a $50 Daisy Vigilante CO2 pistol. When I change the cartridge I "dry fire" 3 or 4 shots. Those are considerably louder than the next 55 or so shots and I suspect those first few might change the POI. After the 55 consistent shots the power drops off and an adjustment would be needed, but at that point I change the cartridge again. No adjustments to the red dot have ever been needed. I would expect a more expensive gun, rifle or pistol, would show at least similar results. If not, there may be a more serious issue with the gun.
...but it also brings up another question. If you re-zero when changing the CO2, do you also re-zero as that CO2 is used up? The rifle should regulate the CO2 for consistency from shot to shot.
I have a $50 Daisy Vigilante CO2 pistol. When I change the cartridge I "dry fire" 3 or 4 shots. Those are considerably louder than the next 55 or so shots and I suspect those first few might change the POI. After the 55 consistent shots the power drops off and an adjustment would be needed, but at that point I change the cartridge again. No adjustments to the red dot have ever been needed. I would expect a more expensive gun, rifle or pistol, would show at least similar results. If not, there may be a more serious issue with the gun.
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CO2 used in airguns does not experience pressure changes across the shot profile, that is until the CO2 is used up and pressure begins to drop.
CO2 in a cartridge (12 gram or 88/90 gram) is in a liquid form due to the pressure maintained by the sealed cartridge. Once you pierce the cartridge the CO2 begins to transition from liquid to gas (it's boiling point is well below 70 F) but the gas is still contained within a sealed chamber - this time in the gun's pressure tube. Only a small amount of CO2 turns from liquid to gas since the released gas pressurizes the larger pressure tube of the gun and recreates the conditions that keep most of the CO2 in liquid form. As you shoot each pellet a small, metered amount of CO2 gas escapes from the gun's pressure tube and the resulting incremental drop in pressure within that tube allows a little more liquid CO2 to transition into gas and so restore the pressure conditions to a balance of liquid/gas mix in the tube.
This process is repeated over and over as shots are fired until there is no liquid CO2 left in the pressure tube. At this point the CO2 is all in gas form and with each successive shot more gas is depleted from the tube with no reservoir of liquid CO2 present to pressurize the tube again. You begin to see less speed on each shot because there is less and less pressure waiting to be released.
The thing to note is that, so long as there is a combination of both liquid and gas CO2 in the pressure reservoir, the pressure level remains pretty constant. Unlike a PCP where the pressure begins at some point (say, 3k psi) and steadily drops with each shot, a CO2 gun should have a consistent pressure profile across a set number of shots until the CO2 has all transitioned from liquid to gas and so loses the facility of maintaining the pressure in the gun's tube. Thus a CO2 gun acts in many ways like a PCP with a regulator; the aim of both systems is to provide the shooter with a consistent outflow of air/gas that provides a metered amount of energy for each shot.
I hope this helps you sort out your question. If you aren't getting consistent shots out of your CO2 then I'd be looking for either a leak somewhere around the breech port of the gun (inconsistent delivery of the gas at the pellet) or a problem with the gun's barrel (burrs or a bad crown). If you aren't hearing a hissing leak around the pressure valve or pressure cap of your gun's pressure tube then your problem is NOT a variation in the pressure of the gas reservoir.
CO2 in a cartridge (12 gram or 88/90 gram) is in a liquid form due to the pressure maintained by the sealed cartridge. Once you pierce the cartridge the CO2 begins to transition from liquid to gas (it's boiling point is well below 70 F) but the gas is still contained within a sealed chamber - this time in the gun's pressure tube. Only a small amount of CO2 turns from liquid to gas since the released gas pressurizes the larger pressure tube of the gun and recreates the conditions that keep most of the CO2 in liquid form. As you shoot each pellet a small, metered amount of CO2 gas escapes from the gun's pressure tube and the resulting incremental drop in pressure within that tube allows a little more liquid CO2 to transition into gas and so restore the pressure conditions to a balance of liquid/gas mix in the tube.
This process is repeated over and over as shots are fired until there is no liquid CO2 left in the pressure tube. At this point the CO2 is all in gas form and with each successive shot more gas is depleted from the tube with no reservoir of liquid CO2 present to pressurize the tube again. You begin to see less speed on each shot because there is less and less pressure waiting to be released.
The thing to note is that, so long as there is a combination of both liquid and gas CO2 in the pressure reservoir, the pressure level remains pretty constant. Unlike a PCP where the pressure begins at some point (say, 3k psi) and steadily drops with each shot, a CO2 gun should have a consistent pressure profile across a set number of shots until the CO2 has all transitioned from liquid to gas and so loses the facility of maintaining the pressure in the gun's tube. Thus a CO2 gun acts in many ways like a PCP with a regulator; the aim of both systems is to provide the shooter with a consistent outflow of air/gas that provides a metered amount of energy for each shot.
I hope this helps you sort out your question. If you aren't getting consistent shots out of your CO2 then I'd be looking for either a leak somewhere around the breech port of the gun (inconsistent delivery of the gas at the pellet) or a problem with the gun's barrel (burrs or a bad crown). If you aren't hearing a hissing leak around the pressure valve or pressure cap of your gun's pressure tube then your problem is NOT a variation in the pressure of the gas reservoir.
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Ironlion269 that was a great write up!
OP how much experience do you have with CO2 guns and airguns? I’m assuming you can see, feel and hear the gun shoot different as you run out of co2 or put a new cartridge in so that makes me think you’re saying that you’re gun changes POI points every time you change CO2 for the entire string and is only consistent relative to the current fill. If that’s the case my first assumption is the barrel some how. Second as mentioned above would be a leak third, a combination of both as always make sure everything is tight and fits good
I love CO2 but the benchrest shooter in me stresses about the power drop offs towards the end of a fill. If I can, the first mod for me is bulk fill.
OP how much experience do you have with CO2 guns and airguns? I’m assuming you can see, feel and hear the gun shoot different as you run out of co2 or put a new cartridge in so that makes me think you’re saying that you’re gun changes POI points every time you change CO2 for the entire string and is only consistent relative to the current fill. If that’s the case my first assumption is the barrel some how. Second as mentioned above would be a leak third, a combination of both as always make sure everything is tight and fits good
I love CO2 but the benchrest shooter in me stresses about the power drop offs towards the end of a fill. If I can, the first mod for me is bulk fill.
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I don't have the same problem in my Walther CP99 Co2 Pistol.
I mounted a red dot sight on it, haven't had to adjust it from a full Co2 bottle to near empty. I normally don't "shoot" till the bottle is empty. Once I can hear the sound drop, a few more rounds then add a fresh Co2 bottle (or move to another gun..!). Seems odd that a rifle would be more sensitive than a short barreled hand gun.
Mike
I mounted a red dot sight on it, haven't had to adjust it from a full Co2 bottle to near empty. I normally don't "shoot" till the bottle is empty. Once I can hear the sound drop, a few more rounds then add a fresh Co2 bottle (or move to another gun..!). Seems odd that a rifle would be more sensitive than a short barreled hand gun.
Mike
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Yeah, I was pleasantly surprised with the shot count. I used it for two years in my local club competition.
We shot a total of 26 pellets in a match. I would get two matches, over two weeks, from a cartridge.
The other thing that people often complain about is the CO2 leaking if the gun sits for a few days.
A small drop of Pellgun oil on each cartridge and that Vigilante has sat for several weeks without leaking.
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