Questions about the mag sear...

[Arstron]

I was doing some thinking today, and ended up asking my self "What makes the trigger pull on a mag hard/light." Here is what I came up with as the best explanation for me.

Since there is always air in the dump chamber, there is a constant pressure put on the bolt, which is held by the sear. My thinking is that the pressure put on the sear is what makes it hard to pull the trigger on a mag. With a ULT kit or smaller on/off pin, it lets the sear sit lower on the bolt which gives it less travel and lightens the trigger pull.

If that is the case, would it be possible to create a second type of on/off pin between the dump chamber and the bolt so that a pin would be pressed instead of the sear releasing the bolt? The sear would have to be redesigned as well of course, but i belive it would make for a very light trigger pull.

I know that this would take an almost complete redesign of the valve, but my main questions are, would it work like im wanting it to, and would there be any significant problems with it?


edit:

Also, this is somthing I just thought about, considering that the sear/bolt is what makes the trigger pull hard, would it be possible to create a new sear that could barely hold the bolt in place, but not wear as bad? This would allow you to keep a longer on/off pin which would give you more reactivity over a shorter on/off pin right?

[Asym]

The reason for the heavy pull is because of the amount or pressure on the on/off pin. The on/off is basicaly a pneumatic ram, air pressure pushes it back out when you release the trigger. Without changing the amount of pressure your only way to reduce the amount of force it is generating(hard trigger pull) is to reduce the size of the piston(on/off pin). wala ULT

The force to slide the sear off the bolt isn't a whole lot, you can prove this with the ULT, the same amount of force is still pushing on the bolt with or without ULT but the ULT drops the amount of force needed to activate the trigger. The ULT reduces the pressure on the back of the pivot on the sear not the amount of pressure being applied behind the bolt.

In the early days of Mags people did try to do some mods to help release the bolt like polishing the sear so it would slide of much easier, notice you don't hear much about this anymore because it caused more problems with sears working corectly.

As for adding the second pin in the dump chamber. Sounds like your just adding another on/off and it would just make another dump chamber, or did you want it to replace the sear or bolt retention?

Edit.....There isn't always pressure in the dump chamber, when you pull the trigger the on/off top shuts the air passage to the dump chamber allowing the spring to return the bolt back. Also ULT doesn't let the sear sit lower, it has to be the same length or the sear wouldn't catch the bolt, if your on/off doesn't stop air flow you get full auto since the bolt never resets.

[ScatterPlot]

Actually a couple technicalities...

There isn't always pressure in the dump chamber, but I think he meant that there is always pressure when the gun is cocked and the sear is "up"

Also, without an on/off the gun wouldn't go full auto, since the bolt would never come back fully- it would find sort of an inbetween point of foreward and back, with air pressure countering the bolt spring's force, and just venting air like crazy. So it wouldn't shoot paintballs, it would just empty the tank for you.

Just my 2 cents.

[Arstron]

The reason for the heavy pull is because of the amount or pressure on the on/off pin. The on/off is basicaly a pneumatic ram, air pressure pushes it back out when you release the trigger. Without changing the amount of pressure your only way to reduce the amount of force it is generating(hard trigger pull) is to reduce the size of the piston(on/off pin). wala ULT

This was the first and obvious conclusion that I got, but what made me change my mind about it, is I thought the only diffrence in the piston is the lenght, the actual diamater is still the same isnt it? Adding shims, and making the pin shorter is what causes the lighter trigger pull isnt it? This is why I thought it was the force on the bolt, since the pin would be shorter, the sear would sit higher at the pin and lower at the bolt right?

The force to slide the sear off the bolt isn't a whole lot, you can prove this with the ULT, the same amount of force is still pushing on the bolt with or without ULT but the ULT drops the amount of force needed to activate the trigger. The ULT reduces the pressure on the back of the pivot on the sear not the amount of pressure being applied behind the bolt.

Yes, the amount of pressure on the bolt is regulated by the regualtor.

In the early days of Mags people did try to do some mods to help release the bolt like polishing the sear so it would slide of much easier, notice you don't hear much about this anymore because it caused more problems with sears working corectly.

As for adding the second pin in the dump chamber. Sounds like your just adding another on/off and it would just make another dump chamber, or did you want it to replace the sear or bolt retention?

This would replace the sear and bolt retention and nothing else.

Edit.....There isn't always pressure in the dump chamber, when you pull the trigger the on/off top shuts the air passage to the dump chamber allowing the spring to return the bolt back. Also ULT doesn't let the sear sit lower, it has to be the same length or the sear wouldn't catch the bolt, if your on/off doesn't stop air flow you get full auto since the bolt never resets.

I know that there isnt always air presure in the dump chamber, but there is always pressure there until the trigger is pulled, which releases the bolt and shuts off the air. The front of the sear catching the bolt keeps the bolt in check, but of course without the on/off it would go full auto for as long as you held the trigger down.

My biggest question now is, how does adding shims or a shorter on/off pin make the, I am no expert only a home tinkerer and thats why im asking, but I thought the diamater of the piston is what determined the amount of force.

scatter, thanks, that is what I meant about the dump chamber. As far as no on/off pin, without the on/off pin, air would simply leak out of the on/off assy. and wouldnt make it to the bolt. If the on/off hole is sealed, the sping will actualy push the bolt back so the air can push it forward again. I have tried this once without a sear in my gun.....

Just so you know, I am not trying to argue with your answers in anyway, im just trying to learn more then i do about how mags work.

[Asym]

didn't think you were argueing, so np. Was more worried that you would have thought I was coming off a little arogent, but was just trying to explain how the valve works which made me think more about certain design features of the valves themselves. But I'm the same way, I want to know how things work so they must be torn apart to be examined and made better(home tinker also).

My biggest question now is, how does adding shims or a shorter on/off pin make the, I am no expert only a home tinkerer and thats why im asking, but I thought the diamater of the piston is what determined the amount of force.

not sure what the question is here though, but it almost sounds like your asking how adding shims make the on/off lighter? If that was the question it doesn't make it lighter, it allows you to adjust the length of the pin which affects recharge and every gun has slight variences on how long it really needs its on/off to be. ULT is much more finkey meaning since its smaller and doesn't have as much push behind it, it has a better chance of sticking or not working if it is too long. With standard diameter on/offs they are a much heavier pull so you have a larger fudge factor and it can be too long, old trigger jobs offered by some airsmiths included grinding your pin to the right length. The ULT is also much smaller hole which is more restrictive than the stock on/off, so you want the pin to only be long enough to shut off the valve but not too long that it would restrict your recharge. The diameter of the pin along with the amount of pressure is what determines the amount of force on the trigger. If that wasn't your question sorry for getting a bit long winded.


Answering your questions just raised new questions that I'm now wondering about. Since The classic valve internal pressure is roughly 400PSI and the Xvalve is around 800ish PSI is the ULT lighter when installed in a classic valve?

[ScatterPlot]

I think the internal pressures are the same on both.

[PsychoBaller]

So basically... in assistance for my Pirate Stock Project (look towards the bottom of the thread for my Ring Trigger Idea) - http://www.automags.org/forums/showthread.php?t=180543 I could simply put an ULT kit in the Mag, and make it easier to pull? I'm lookin towards putting a Ring Trigger thing directly attached to the Trigger Rod... which is directly on the sear. People have been telling me its gonna be a lot harder force to pull the trigger... but if i have an ULT, it shouldnt be as such ???

-baller

[Arstron]

not sure what the question is here though, but it almost sounds like your asking how adding shims make the on/off lighter?

Yes that was the question, I didnt proof read my post.....

If that was the question it doesn't make it lighter, it allows you to adjust the length of the pin which affects recharge and every gun has slight variences on how long it really needs its on/off to be. ULT is much more finkey meaning since its smaller and doesn't have as much push behind it, it has a better chance of sticking or not working if it is too long. With standard diameter on/offs they are a much heavier pull so you have a larger fudge factor and it can be too long, old trigger jobs offered by some airsmiths included grinding your pin to the right length. The ULT is also much smaller hole which is more restrictive than the stock on/off, so you want the pin to only be long enough to shut off the valve but not too long that it would restrict your recharge. The diameter of the pin along with the amount of pressure is what determines the amount of force on the trigger. If that wasn't your question sorry for getting a bit long winded.

I guess I miss understood the ULT, I will have to compare the size of my ULT pin to my stock pin. I have done quite a few on/off pin mods, the only thing they really do is shorten how far the on/off pin has to fire the gun, which shortens trigger pull. After playing around with my rt rail with sear and a peice of metal, I realize that the bolt couldnt effect the strenth of the trigger pull at all, but could make it lighter. As the bolt moves forward, it helps to push the sear down when its fireing. I would imagine the force needed to pull the trigger would be even greater without the front half of the sear catching the bolt.


Answering your questions just raised new questions that I'm now wondering about. Since The classic valve internal pressure is roughly 400PSI and the Xvalve is around 800ish PSI is the ULT lighter when installed in a classic valve?

Both valves internal pressure is around 400 psi, the external pressure can be anywhere from 600psi+. This leads me to another question, people say that a tank set to a higher psi, usualy 900+ will give an automag RT more bounce. With this in mind, and what you said, is the main diffrence in the RT and classic valve that the unregulated pressure is what activates the on/off pin for an RT and the regulated pressure is what activated the on/off pin on a classic? i've never thought about that before...

[Arstron]

So basically... in assistance for my Pirate Stock Project (look towards the bottom of the thread for my Ring Trigger Idea) - http://www.automags.org/forums/showthread.php?t=180543 I could simply put an ULT kit in the Mag, and make it easier to pull? I'm lookin towards putting a Ring Trigger thing directly attached to the Trigger Rod... which is directly on the sear. People have been telling me its gonna be a lot harder force to pull the trigger... but if i have an ULT, it shouldnt be as such ???

-baller

If you want to test it out, take the grips off of a trigger frame, gas the gun up and pull on the sear instead of the trigger, that is how much force there will be to pull the trigger.

[Dayspring]

Correct. The RT on/off gets unregulated pressure and the classic gets regulated pressure. (There is a pressure feedback loop to the reg piston that allows it to shut when it gets to the proper psi in the dump chamber.)

Secondly- you guys are somewhat confused as to how the sear moves. It doesn't slide off the bolt. It moves in an arc away from the bolt.

Both valves internal pressure is around 400 psi, the external pressure can be anywhere from 600psi+. This leads me to another question, people say that a tank set to a higher psi, usualy 900+ will give an automag RT more bounce. With this in mind, and what you said, is the main diffrence in the RT and classic valve that the unregulated pressure is what activates the on/off pin for an RT and the regulated pressure is what activated the on/off pin on a classic? i've never thought about that before...

[Arstron]

Correct. The RT on/off gets unregulated pressure and the classic gets regulated pressure. (There is a pressure feedback loop to the reg piston that allows it to shut when it gets to the proper psi in the dump chamber.)

Secondly- you guys are somewhat confused as to how the sear moves. It doesn't slide off the bolt. It moves in an arc away from the bolt.

Thanks for clearing that up, it would mean that a ULT on a classic valve would be lighter considering the stock classic on/off pin is smaller in diametor then the ULT. Hmm, I wonder how much smaller the on/off pin could be....

As far as the sear going in a arc motion, I didnt think about that until my last post, this is why I said the bolt som what helps to push the sear forward and lighten the trigger pull.

What if you pluged the air port that pushed the on/off pin and added a spring in there. Wouldnt this lighten the trigger pull greatly. Finding the right spring strength could be tricky, but once you got it just strong enough to push the on/off pin and lock the bolt, you should have a very light trigger pull. Then the only factor would be having enough pressure on the sear to keep the bolt from moving....

[PsychoBaller]

Careful with custom shortening the On/Off pin.... will be very reactive. TUNA did some modifications to his son's Mag couple yrs ago... You could breathe on the trigger and it would go off, heh.

[Arstron]

I didnt mean shortening, ive done that plenty of times before, i meant making the diameter of the pin smaller.

[Asym]

Thaks Dayspring, didn't realize the RT/X valves used unreg'd pressure on the on/off. Still playing with a classic with ULT.

[k0m0d067]

ok...there is ALOT of information flying around here, and it's very late...LOL

so rather than try sorting thru all of this, i'm gonna just ask my question (which was probably already answered in one of the above posts)...

what valve has the lightest trigger pull? with or without the ULT kit...i don't care about reactivity, as i'm building an experimental electro frame for my mag, but i'm having concerns regarding the strength of my solenoid...

is the classic valve trigger pull lighter? (thought i saw that mentioned somewhere above) and would a ULT kit help a classic valve? (read a couple times that the ULT doesn't really help a classic valve much)