Pro-classic Shoot down

[WAH11AU]

I have a couple of pro-classic's im trying as field rentals, the only problem i have run into is with shoot down.
After the gun has been gased(co2) up for about 3-4 hours, when you go to shoot them after a short break the first couple of shoots the ball will only go aout 20-30 feet.After you shoot about 5-10 shoots it seems to build up pressure again and runs like normal.
Is there something simple i am missing here????
I thought mags weren't affected buy heat like other blow backs.????

Thanks

[Coralis]

Hmm thats a wierd problem .... usually shoot down on a mag is caused by rapid fire and the subsquent cooling of the tank/lowering out put pressure of CO2 .... what this sounds like to me is perhaps the Orings are absorbing some liquid CO2 and swelling some ( im really reaching here ) what type of set up do you have for your CO2 ? Vertical bottle or bottom line and expansion chamber etc. You might try really oiling the guns prior to days play to fully coat the orings to see if that helps.

[paint magnet]

I have a couple of pro-classic's im trying as field rentals, the only problem i have run into is with shoot down.
After the gun has been gased(co2) up for about 3-4 hours, when you go to shoot them after a short break the first couple of shoots the ball will only go aout 20-30 feet.After you shoot about 5-10 shoots it seems to build up pressure again and runs like normal.
Is there something simple i am missing here????
I thought mags weren't affected buy heat like other blow backs.????

Thanks

Mags are blow-foward, not blowback. They aren't affected by heat, but do have poor cold-weather performance on CO2. While I'm not sure of the cause of your problem, oil may help (it seems to work wonders lol)...if that doesn't work I guess you could always just shoot the gun ten times before renting it out. If it really bothers you though, call AGD.

If they are new, it may just be a break-in issue as well.

[WAH11AU]

Hmm thats a wierd problem .... usually shoot down on a mag is caused by rapid fire and the subsquent cooling of the tank/lowering out put pressure of CO2 .... what this sounds like to me is perhaps the Orings are absorbing some liquid CO2 and swelling some ( im really reaching here ) what type of set up do you have for your CO2 ? Vertical bottle or bottom line and expansion chamber etc. You might try really oiling the guns prior to days play to fully coat the orings to see if that helps.

I have just the standard setup with the bottom line.
When i first set them up in the morning the first shot fired out of each of the guns spikes to about 350fps and then the following shots are between 290 and 300fps.
After they are set up for about 4 hours it seems to change and the first 5 shots start at about 200fps and then work there way up to shooting close to 300fps.
I am at a loss to explain it, i have never had mags do this before.???

Its not a break in problem, they worked perfect for the first 8 weeks without any problems.

[BigEvil]

How many guns are doing this?
Are you using micro line by any chance?

-replace the reg seat
-clean and lube the piston and piston oring
-make sure there are no foreign objects in the air pathway, such as bits of teflon tape.

[Coralis]

some more questions

If I had to wager a guess it sounds like your getting some liquid CO2 in the gun while they are setting , do you have them in a rack and its the back of the bottle higher than the valve part of the bottle when they are setting. Do your CO2 bottles have anti siphon tubes in them, though this will be moot if the guns are sitting on their sides. If you have access to a compressed air bottle you could hook one up and test it to see if the problem is airsource related or if you need to start replacing Orings and reg seats in your guns.

[SpitFire1299]

If I had to wager a guess it sounds like your getting some liquid CO2 in the gun while they are setting , do you have them in a rack and its the back of the bottle higher than the valve part of the bottle when they are setting. Do your CO2 bottles have anti siphon tubes in them, though this will be moot if the guns are sitting on their sides. If you have access to a compressed air bottle you could hook one up and test it to see if the problem is airsource related or if you need to start replacing Orings and reg seats in your guns.

I was also thinking that. The liquid co2 probley filled up in the valve.. and only let liquid out at the ball.

[WAH11AU]

I was also thinking that. The liquid co2 probley filled up in the valve.. and only let liquid out at the ball.

Thanks for the advice guy's

[athomas]

Seems like something is sticking. Try cleaning and lubricating.

A first shot drop usually indicates a loss of pressure in the chamber. Check for leaks.

Gradual buildup of velocity/pressure is an indication that something isn't moving as freely as it should.

[Ole Unka Phil]

Naw some of you got it bassackwards... Shoot down is being caused by the Gas entering hot and then cooling down when left in the chamber so it condenses and loses Pressure. If the markers are set up after a good few shots they are going to shoot down if left to cool off. Two things here could be the culprit. Lack of a good Expansion chamber/stabilizer and or poor Seal or Regulator seat.

CO2 is hard on orings in the on off and the plastic reg seats. I would replace those often. And never shoot a mag without a good regulation system in line like a Expansion Chamber or a Palmer Stabilizer reg. They just don't like it. You should not set up a Field mag for CO2 without some type of device to minimize this transition. Because the mag valve recharges so fast. Even the classic valve. Which is the Rental valve with a few minor modifications to limit velocity. So its going to give you the same recharge and stability issues to overcome using CO2. That being said... they work very well on CO2 when set up properly.

But to a small extent... if the marker is rapid fired and then velocity set (which you normaly would do) and there is no stabilizer between its valve and its Supply of CO2.... its going to shoot down for a couple shots while it heats back up. As long as its not getting liquid into it that is...

If there is liquid getting into the valve the Gas is then going to expand when let sit.... and shoot up. Not down. Which is, or can be, dangerous. Let alone eat up orings fast and perhaps blow the over pressure outlet of the Valve. The little icey crystals can cut orings and or make them freeze up and get brittle and crack. Its hard on them. So its normal to replace them fairly regular on a CO2 marker. But can be minimized by properly regulating the CO2.

And I should mention a properly set up Anti Siphon valve should be in those CO2 tanks. By properly set up I mean oriented when installed to take Gas from the top and not from the bottom when the tank is completey screwed onto the ASA. Does not sound like your problem. But is a common problem in rentals because the tanks don't always stay with that particular Marker and its ASA... so thier orientation may or may not be right from Marker to marker. And should be or they are worse then no Anti Siphon at all if they are erroneously oriented to pick up liquid from the bottom. Again your not describing that problem. Just wanted to mention that part because its one step in the proper set up of a Mag on CO2. And hard to do in rental applications if you cannot keep the tank with that marker.

In your case I would start by replacing the Regulator seats. That plastic disc on the back of the Reg pin. And examine your set ups. Install Anti Siphon tanks if they are not there and put Stabilizers on the tanks.

But even so... a little shoot down for a few shots if the marker is fired rappidly and then sat to cool off (more prevelent in cold weather) is going to be normal with ANY marker on CO2 in cold weather. Thats a natural charicteristic of CO2 as a Gas vs Liquid state. And one of the reasons so many have gone to HPA.