Pistol + propane + cold
 

Hi there
I received a pistol yesterday and everything is nice but there's a problem...
Im indoor, and after 40 bbs the mag get cold, the slide dont lock and can even spit something on my hand (maybe propane...).
Is it normal for any pistol with propane (with AI adaptor and oil) ??
Thank :/

ya thats normal. my TM 1911A1 could barely empty its 24 round mag with a single charge. but if you dont rapid fire your pistol it gets better. i find warming the mag in my hand prior to rapid firing the gun tends to be able to squeeze the last rounds out but slide might still not lock back.

today i bought some Trecel mags for my single stack 1911 and i was able to dry fire it 40 times before the gas runs out so im not sure if that mag holds more propane or dry firing uses less gas. but it seems to be an exact copy of my TM mag except 40 bangs VS 20 something bangs

dry fire on a gas gun uses less gas. it take gas to send a BB down the barrel, remove that step and that gas isn't used.

? dry firing uses less gas?? How?

When the firing pin strikes the striker valve it doesn't know if there's a BB in there or not and will expel as much gas as it's designed too... until the mag has no more gas to expel...

Actually the way gas guns are designed, it waits until the BB is out of the barrel then the change in pressure (or loss in backpressure, however you want to call it) changes the nozzle from BB-projecting flow to slide-recoiling flow.

sorry, but most GBBs have a valve system in them that directs gas either forward into the barrel or back to cycle the weapon. when a BB is fired, the valve stays in the back position letting gas into the barrel. as long as that BB is there the gas pressure keeps the valve back. once the BBs leaves the barrel, the pressure drop along with the valve spring(in the case of the positive pressure setup) will then push the valve forward blocking off the barrel and directing the gas now into the expansion chamber so the weapon can cycle. it's the cycling that resets the valve striker (firing pin), it never releases a per-determined amount of gas.

the two types of valve systems are as follows.

positive pressure system: the valve is normally in the forward (barrel closed/sealed via spring behind valve) position unless a BB is chambered and pushes the valve back (open) position via a protrusion extending forward of the valve. (there are many design variations of this but the function is the same.)

negative pressure system: the valve is normally in the back (open, via spring) position regardless if a BB is chambered or not. the valve will only close once the BB leaves the barrel. once the BB is out the pressure inside the barrel and thus on one side of the valve drops. this creates a pressure difference between one side of the valve and the other. when the difference is large enough to overcome the pressure of the spring keeping the valve back, the valve is sucked forward and closes off the barrel, at which point the system will cycle.

so as i said, remove the steps involved in pushing a BB out of the barrel and the gun uses less gas. worth noting, the negative pressure system will use more gas than the positive during dry fire, as the valve starts in the open position.

great explanation, so how do upgrade valves work? maybe different springs or orifices or something else?

but my point is, the same amount of gas is expelled out of the mag regardless of there being a BB or not... How does the hammer and the mag know there's a BB in there... don't care what happens to the gas after the striker valve is hit as you said, "dry fire on a gas gun uses less gas." That's what's not making any sense to me... you and Jeff gave me an explanation on what happens after the valve is hit by the hammer...

Meh, whatever... OP use less BB's and see what happens; instead of 40, try 20...

a stronger spring that requires more force to close it, and the way the valve is shaped to redirect the gas flow in either direction. take a look at the NPAS on a WE, by adjusting it forward you get less fps, because more gas is directed to the rear. by adjusting it to the rear, it allows more gas directed into the chamber.

The way that the valve works is pretty smart. The valve they're talking about is in the chamber, not the mag. its used directionally to split the gas entering the nozzle for two functions, to propel the bb and to activate the blowback mechanism. The valve moves back and forth, due to pressure. When there is a bb still in the barrel, the pressure of the gas behind it keeps the valve balanced and counteracting the force of the rest of the gas behind it trying to force it closed. Once the BB leaves it though, the pressure is interrupted, and closes the valve, starting the blowback mechanism.

so if you dry fire, there is no bb to keep the pressure in the barrel, and while some of the initial gas is vented through, the valve closes much quicker with no bb's than it does with a bb in the chamber, therefore using less gas.

^ +1

the hammer and mag are mechanical components and are not capable of knowing anything. the valve on the mag is closed when the hammer resets, which only occurs when the slide cycles and resets the hammer. thats why dry fire uses less gas, the slide cycles right away instead of waiting for the BB to clear the barrel. the amount of gas used to propel the BB is: the volume of the barrel from hopup to mussel, multiplied by the pressure (psi or bar).


here's a brake down on how it all works.. or maybe a powerpoint presentation with pictures would be more helpful?

ok.. at the start with the gun ready to fire. mag inserted, hammer cocked.

you pull the trigger and release the hammer, hammer travels forward and strikes the valve striker (firing pin). the valve striker now pushes the valve in the mag open where the gas starts to flow.
(positive pressure valve system) BB is loaded and sits inside the hopup chamber. it applies physical pressure against the flute on the valve keeping it in the open position. once the gas makes its way up the gas port, it is directed forward towards the BB and hopup. the BB now starts to accelerate due to the gas pressure building up behind it, until it reaches the end of the barrel where it then proceeds to your target.

once the BB has exited the barrel, the pressure inside the barrel drops. since there is a pressure difference now between the barrel side and the expansion chamber side of the valve, the valve is sucked forward and seals the barrel. the moment the barrel is sealed, all the gas is now redirected into the expansion chamber. the slide starts to cycle and re-cocks the hammer, releasing the valve striker and thus releasing the valve in the mag, cutting off the gas supply.

(negative pressure valve system) mag in, BB loaded and hammer cocked.

trigger is pulled, same exact thing happens as explained above. the difference is how the valve inside the slide works. the valve is kept in the open position by a spring. once the BB leaves the barrel, once again the pressure difference between the barrel side and the expansion chamber side overcomes the force of the spring and seals the barrel, at which point the slide cycles and re-cocks the hammer and the valve in the mag.

if you understand that, then you can see how removing the BB from the barrel would reduce the amount of gas used for every cycle the weapon is fired. the volume of gas that would have been used to propel the BB is not used. this also makes the gun cycle sooner or faster as it has skipped the action of pushing the BB out the barrel before it cycles the slide.

i hope this clears it up for you, and if not, then you are either trolling or should stop explaining to others how you think something you have no idea works.

Going to have to disagree. Even your explanation tells me that there's just more has directed at the cocking effect. It seems the same amount leaves the striker.

incorrect. The valve knocker is kept down until the slide begins the cycling process. It takes longer for the valve inside the nozzle to close when there is a BB compared to when there isn't one, delaying the cycling process and keeping the magazine valve open longer, therefore using more gas.

.. gas is being used through out the cycle so long as the valve in the mag is open. with a BB traveling down the barrel, gas is being used to push it out. if you don't have a BB the slide cycles right away and gas that would have been used to push the BB out is instead directed to cycle the slide. since that step of pushing the BB out is skipped, the slide cycles sooner and cuts off the gas sooner thus reducing the amount of time the valve on the mag is open. so less gas IS used when dry firing.

in the simplest terms that i can think of.. the amount of gas used in a gas gun is completely dependent on how long the main gas valve is kept open. that is determined in the case of a pistol by the slide, as it is what re-cocks the hammer and resets the valve striker.

every action the gun goes through during the firing cycle takes a set amount of time. during which the main valve is open and expelling gas. removing one of the actions (propelling a BB) reduces the cycle time and thus reduces the time period at which the gas valve is open.

Ah I thought the valve opened and released a certain ammount. Apparently not. Thx

that's what i thought too... still dont care... but thx tho... and powerpoint would be AWESOME!