Reason for the start of a Mag pull being so light

[QUINCYMASSGUY]

OK, got a great question for some of the great minds on this board: what makes the start of the pull of a Mag trigger so much lighter than the rest of the pull? Is it the angle the sear extension is moving or something, where as it's not providing as much force in the direction towards the grip frame and more force downwards or something? I have no idea why it would be so light as the pressure pushing down on the on/off pin would be the same through most of the stroke right? Help me out, thank you.

[Thorpydo]

Don't own a mag or know what the trigger pull feels like but I'm guess that its from the on/off pin. Theres two actions in the trigger, the sear and the on/off. Trigger will have a pretty constant force until the pin is sealing the chamber off, and then your pushing against the pin also.

[QUINCYMASSGUY]

maybe

I think it might be something along that nature but if that was true you wouldn't still have it with the ULT I think, the point where the on/off seals the chamber and the firing point are so close yet that lightness part hasn't changed at all. The part where air is pushing is the heavy part and that's dropped to 15oz but I think there's something more than it than that. Good point though and who knows, it could be right.

[QUINCYMASSGUY]

Up

Up, anyone with indepth knowledge of mags, can you help me out with this? Thanks!

[AGD]

actually the start is harder than the finish in classic valves. At the beggining of the stroke you have the force of the bold latch plus the forced of the on off pin. Once you pull the sear off the bolt the force goes down.

AGD

[QUINCYMASSGUY]

cool

Cool, I appreciate the response Tom. One quick followup question: You definitely implied that for classics it is harder, so is it something to do with the setup of the retrovalve or the lvl 10 that makes the start lighter on mags with the RT or X Valves? It definitely seems like the first initial bit is real light. Would any change in the setup make the whole pull the same weight without risking the bolt not being able to fully reset? I am sure you have seen my various posts (spring idea, etc), just trying to get a better understanding of the functionality of Mags so my thoughts are logical and coincide with your intent as you definitely know tons about how Mags work that I am sure I don't. I truly appreciate the input and the help and do understand that if I or any other AOer used any of this knowledge to modify their Mag it would be their responsibility and their fault for any damage, hence no warranty service. I hope to hear more, thanks again.

[classicmagplayer]

i'm going to take a stab at this...
there are a few things that affect the weight of the pull
1. the pressure on the on/off pin
2. the friction where the o-ring seals on the on/off pin
3. friction on the bolt

now how each is changed as you pull the trigger
1. Pressure on the on/off pin wont change much. THe only way for the pressure to change would be a change in volume. Which there is, because the on/off pin is being inserted farther into the valve. But that is such a small volume it wont make a difference.

2. Static friction is always less the kenetic friction, so the friction of the seal should actually go down once the pin starts moving.

3. Same as above. Once the sear starts moving down the bolt the friction should become less, therefore decreasing the force required.


THe only reason i can think of your pull being harder at the end than it is at the start would be your sear is pushing the bolt back into the powertube...which would create a larger change in volume....and in turn, an increase in pressure that is pushing the on/off pin. Or it could be that the kick of the trigger is seperating the on/off pin from the sear and what you are feeling at first is just the friction of the sear on the bolt.

probably more, but i'm not going to write it all since i have homework to do.

[QUINCYMASSGUY]

pull

Classic, that all actually does make sense, but with my setup of XValve/Intelliframe, I definitely noticed that the first little part of the pull is way lighter than nearer to the point of firing and it's the same with the return, at about the same point in the return the retro effect becomes nonexistent so that if pressure was still applied to the trigger (like the avg of 15oz that it takes to fire) the sear won't fully reset. Your points would definitely be valid for a non-Retro valve but in the case of the X it seems the logic is reversed. Something is making that first little bit lighter, starting just after you start pulling the trigger it becomes real light and it's the same place on the reset it is definitely way below the weight usually applied by the retro effect. Any thoughts on that?

[classicmagplayer]

is this with the ult?

If it is, what you might be feeling is the top o-ring sealing on the top of the on/off pin. If you add more shims it will hit later...and if you adjust it right it should seal right before the bolt is released. WIth less shims the on/off pin will actually be pushed up through the o-ring making it a stiffer pull since there is more friction.

[QUINCYMASSGUY]

light weight

It is the point from right when you start the trigger pull to a point when the sear is still in front of the bolt preventing it from firing but is pretty close to firing but still has a little ways to go. So it's the first little bit of movement and well before the sear unlatches and lets the bolt go. I do have the ULT in but it did this with the Lvl10 only too, so it is light for this first part and then the last part just before it fires is the heavy pull we are familiar with. I doubt it's my sear malfunctioning, it is in great shape and did it with my older sear and I am confident it is not caused by the ULT. It must be the bolt/sear relationship but I am curious to know why the pull weight balance is one way for classic valves and the other for retros.