Hi all,

This is a multi-post thread I did a while back in the old forum. I'm resurrecting it from my personal archives for the benefit of all mankind!

The purpose of this thread is to discuss the various trigger mods known for the stock trigger, and to specifically fine tune the Response Trigger.

Before modding a trigger I thought I would explain how the stock trigger works. This way you understand how each of the mods works which will ultimately help you fine tune your trigger to work exactly how you want it to. Sooo….

How does the trigger work?

First, lets talk about the pieces of the trigger by definition. I will be using Tippmann’s A-5 parts diagram part names and numbers.


1. Trigger (02-36): this is what interacts with your trigger finger to engage the firing mechanism. The trigger interacts with two pins on the trigger frame, one of them is what it rotates on and the other acts as a forward and backward stop.

2. Trigger Slider (98-18): This is what engages the sear forcing it into a nose up position and releasing the hammer. It is located on the trigger, the silver metal piece with the spring behind it

3. Sear (02-35): this is the “middle man” between the trigger and the bolt. It acts as a “stop” for the bolt to prevent it from going forward automatically after each round.

4. Trigger spring (02-20S): this provides the tension against your finger when you pull the trigger. A stronger spring means a harder pull to engage the system, a lighter spring means less tension to engage the system.

5. Sear spring (Trigger Spring, 02-20): This is the spring that forces the sear upward to engage the bolt

6. Trigger frame (Trigger Plates 02-67 L/R) : this holds all of the components together and aligns them to function properly

7. Rear Bolt (02-11): This is what goes forward to hit the air valve and pressurize the marker. It is tied into the front bolt (02-17) by the linkage arm (98-16).

Basic trigger function in the A-5 (and 98 and Pro Carbine) is something like this:

Pulling the trigger disengages the sear from the bolt and allows the bolt to go forward. The sear also interacts with two pins on the trigger frame, one of them is rotational, the other prevents it from rotating too far downward.

If you look at the sear you could say that it has a “nose” and a “tail”. The nose is what interacts with the trigger and the tail interacts with the bolt. It rotates around it’s center and the sear spring forces it’s natural position (we’ll call this the “nose down” or ND position) to be tail up so that it always automatically locks the bolt to the rear.

With that brief understanding of the parts, lets talk about the cycling action. You can take a look here if you want to know more information about the cycling action. Here's a brief overview:

1
Status: Locked
We will start at the point where the weapon is off “safe” and the bolt is locked to the rear. This is the position where pulling the trigger starts a series of events to make a ball go downrange and get the marker ready to do it again.

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2
Status: Release (The bolt is to the rear and locked there by the tail of the sear in it’s nose ND position.)

Action: Pulling the trigger. When you pull the trigger back it rotates around a pin in the frame. A second pin on the frame prevents you from pulling it back too far. This action lifts the trigger slider under the nose of the sear and puts the sear into the NU (Nose Up) position forcing it to rotate around it’s rotation pin and making the tail to drop which releases the bolt and allows it to go forward.
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3
Status: Fire (Bolt forward) (trigger still pulled)

Action: When the bolt goes forward it also pushes the front bolt forward. The front bolt is the little black thing on the front of the power tube that grabs the ball and pushes it into the barrel. When the bolt gets all the way forward it slams into the air valve inside the power tube. This releases the air into the marker which pushes the ball out of the barrel. There is enough extra air to also push the bolt back towards the rear of the marker.
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4
Status: Re-cock (Bolt traveling rearward) (trigger still pulled)

Action: As the bolt travels to the rear of the marker it passes the excess air vent hole. This hole goes to the outside of the marker through your banjo fitting and into the cyclone ram to recock your cyclone and feed another ball into the chamber. After the bolt passes this hole it slides over the sear pushing the tail down against the force of the sear spring.
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5
Status: Re-Arm (Bolt locking to the rear) (trigger still pulled)

Action: Once the bolt slides completely to the rear and over the tail of the sear the sear spring forces the tail into the locking groove of the bolt. The bolt still has tension on it from the operating spring (pushing forward) which forces engagement to the sear and pushes the sear forward. This forces the sear to engage the trigger slider on the trigger into the forward position.
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6
Status Re-Set (Preparing to fire) (release the trigger)

Action: Releasing the trigger at this point slides the trigger slider down the nose of the sear. The spring behind the trigger slider pushes it to the rear of the trigger and under the sear. When you release the trigger you will hear a muffled click, this is the sound of the slider popping back under the sear.
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Once the slider is under the sear you are ready once again to fire the marker – go back to step one, pull the trigger and repeat ad-nauseum (or until you run out of paint).

Now that we have a decent understanding of how the trigger interacts with the marker system, let’s look at what the R/T does to enhance that system.


The RT is an air fed solenoid that pushes the trigger back into the forward position during the Re-Cocking phase (step 4) of the cycle. The R/T replaces the single sided banjo fitting that feeds air into the cyclone with a double sided fitting. The second side feeds through a restrictor valve and into the solenoid. When the air enters the solenoid it pushes an arm forward into the back of the trigger. This is a mechanical assist to the trigger spring in returning the trigger to the forward position.

How does this help?

The trigger spring, by it’s placement, naturally forces the trigger into the forward position placing the trigger slider under the nose of the sear. The stronger the spring the faster the trigger will go to it’s forward position, but unfortunately the user has to be able to easily overcome the force of this same spring to pull the trigger back. This limitation forces the weight of the trigger spring to be limited. With the forward trigger assist from the R/T the user no longer has to “think” about releasing the trigger to re-fire as the solenoid does that for them.

What are the specifics to getting the R/T up and running?

Well – as with the rest of the marker, it’s a fine tuned system of sealing air from leaking to the atmosphere and forcing the air where you want it. Following the directions provided with the R/T helps considerably in this process. In other words, before asking why your R/T doesn’t work right try doing the following:

1. Read the frigging manual!
2. As with the rest of your marker, make sure that all of your air sources and o-rings are sealed. If the air leaks the R/T won’t R.
3. Read the frigging manual!

Why use an R/T if there is already a spring to do the work for me?

The R/T enhances the effect of the spring. When it is fine tuned and modded the R/T is easily capable of sustained high rates of fire, but is technically not “automatic” fire. Theoretically you could get the same effect as an RT with a stronger trigger spring, but your finger would tire quickly with trying to massage the trigger into a sweet spot against that much resistance.

Sweet Spot? What’s that!?!

The sweet spot is the exact place in the trigger pull (about ½ way back) where you keep constant pressure on the trigger. The R/T will automatically re-set the trigger for you and your pressure on the trigger only allows it to move a fraction of an inch to fire. Finding the sweet spot on an unmodified R/T is possible, but takes lots of initial practice for most people to find it, and even more practice after that to maintain it past 3 to 5 rounds before over stroking (pulling the trigger to hard) or under stroking (not pulling hard enough).

The trigger stop mods

The trigger stop mods assist the R/T in achieving high rates of fire by preventing the user from over stroking (pulling back too far) the trigger. The ideal trigger stop mod will allow you to pull the trigger ONLY enough to nose up the sear to release the rear bolt and no further.

Most users will do a trigger stop mod and be satisfied enough with the results to go no further. Some experimentation will be necessary from marker to marker and if you perform the sear pin mods.

There are three variations of this mod:

1. The Q-Tip mod (and it’s derivative set screw mod)
2. The Straw Mod #1
3. The Trigger Pin mod


1. The Q-tip mod works by placing a small section of a Q-tip (Cotton Swab) stick (not the fuzzy ends!) inside of the trigger spring. Again, this is the spring at the nose of the trigger, and by placing a piece of a Q-tip inside the trigger spring you stop the nose’s downward movement at a designated spot. This stop should coincide with the rear pull of the sweet spot on your R/T’d trigger to prevent you from over stroking.


The common size used with the Q-tip mod is 0.9 cm (centimeters). Experimentation may be necessary to fine tune the size to your marker.

The derivative to the Q-tip mod is to drill and tap a hole for a set screw in the trigger nose. The set screw should be long enough to fully engage the threads in the nose *and* stop the trigger from going down too far. The bonus of this method is that you can adjust the set screw to meet your R/T’s requirements on any give day. Some people that used this method complain about the screw backing out or in and whacking the adjustment. This can be cured with a small amount of blue (non permanent) Locktite on the threads.

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2. The Straw Mod #1 works by placing a piece of “sippy straw” from a Capri-Sun juice bag on the trigger stop pin. In my opinion this method is the best of the three because it not only prevents you from over stroking the trigger, but also prevents you from under stroking it (preventing the trigger from going too far forward) as well. If the trigger goes too far forward it’s that much further you need to pull the trigger to engage the sear to release the bolt.


An alternate to the sippy straw can be an appropriately sized piece of electrical shrink wrap tubing. If you use the shrink tubing you should get the appropriate size that does NOT require you to actually shrink it to the pin. If you try to shrink it to the pin you may wind up swelling the ends of the tubing which will distort the size and shape, and thus adversely affect the function.

Remember the description of the trigger from above – it rotates on one pin and the other is a for and aft stop pin. The piece of straw/tubing you use should be cut no wider than the trigger itself so that it doesn’t interfere with placing the left side cover back on.

Because this method also prevents the trigger from returning completely it will interfere with the safety pin. A slight modification of the trigger resolves this problem and will still allow the safety to work properly. If you look at the trigger you will see a small “hook” shaped protrusion below and aft of the trigger slider. This hook is what is engaged and disengaged by the safety. The big hole in your frame is where the safety passes through, if you reassemble your trigger onto the frame you will notice that this hook goes slightly inside of the hole, get out a file or some fine grit sand paper and remove the tip of the hook so that it doesn’t get in front of the hole and the safety can pass through unobstructed.
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3. The third trigger stop mod also uses a set screw, but this set screw is put through the trigger guard on your grip and points up towards the rear of the trigger. You will need a screw long enough to go through the rear of the trigger guard (near the hand grip), strong enough not to bend under force and long enough to engage the rear of the trigger. It is also adjustable, lengthening or shortening the screw increases or decreases how far back you pull the trigger before it stops.

The Sear Straw Mod
AKA Straw Mod #2

Like the Trigger Stop Straw Mod #1, Straw Mod #2 is using a similar piece of Capri Sun sippy-straw or heat shrink tubing to sleeve the sear nose pin.


Take a look at how the sear operates again. The sear spring pushes the tail of the sear up to engage the rear bolt at the end of the cycling action; it rotates/slides on a pin that goes through the sear in its oblong hole. To control how high the tail of the sear goes up to engage the bolt the nose of the sear itself rests on its own pin. It is the nose pin that you want to sleeve, and here’s why:

Remember back to the discussion of cycling action of the marker. When you pull the trigger the “trigger slide” engages the nose of the sear, lifting the nose to force the tail to drop and release the rear bolt. By sleeving the nose pin you are preventing the nose from going down as far which in turn prevents the tail of the sear from lifting as far. When done properly the tail of the sear will still engage the rear bolt, but with far less “meat”.

Reducing the amount by which the sear engages the rear bolt reduces the amount of trigger pull needed to release the sear from the rear bolt. Used in conjunction with one of the trigger stop mods you can significantly enlarge the “sweet spot” making it easier to both find it and keep your trigger inside of it.

Sleeving the sear pin works very well with the Straw Mod #1 (but not so much with the other trigger stop mods) because it is both a forward and backward stop for the trigger. When done and adjusted properly the R/T will push the trigger forward only enough to release the trigger slider (stopping at the forward position) and you will only be able to pull the trigger far enough disengage the sear tail from the bolt.

The down side to the Straw Mod #2 is that it will increase wear on the rear bolt, the sear tail, or both. This is not a set it and forget it mod, you must perform regular preventative maintenance and service checks (In the military we call this PMCS) on both the sear and bolt, and you would be wise to carry an extra of both should you have accelerated wear.

The worst case scenario is that the sear/bolt wears so far that they no longer engage and you wind up with a “wild fire” weapon. If this happens on the field you may be able to continue play simply by removing the straw on the sear nose pin. You should immediately replace both items ASAP however.

That said I am currently running both of the straw mods and have fired at least 6,000 rounds without failure and showing only minimally accelerated wear over what would be normally expected.

The R/T Trigger stop/slop mod

I’m still thinking of a better name for this mod, any and all ideas welcome. I’m hoping for something more venerable and descriptive than “Psyopper’s trigger mod” though it is always cool to have something named after yourself. 

Once again, lets’ recall how the R/T works: It’s an air powered “solenoid” that when you fire the marker an amount of excess air is bled off of the system to feet the solenoid. This solenoid engages the back side of the trigger to force it forward assisting the user in resetting the trigger for re-firing the marker. If you look at the back side of the trigger (opposite where the users finger engages the trigger) you will notice a molded flat spot – this is the “landing zone” for the R/T’s piston. I noticed that there was a sizeable gap between the LZ and the piston when the piston was fully retracted. This gap meant that there was an amount of time (small, but not non-existent) between the time that you pulled the trigger and the time that there was enough air bleed into the solenoid for the piston to hit the LZ and push your trigger forward.

I negated this gap by drill/tapping a 10/32 hole and filling it with a set screw. This set screw should be short enough that you can screw it completely into the trigger so that it’s flush (returning the trigger - R/T interface to stock Tippmann specs) but long enough that you can back it out roughly 1 to 1.5 mm. The end result is that when your trigger and sear mods are complete, when your trigger is fully pulled to the stop and the R/T piston is fully retracted, the set screw is less than 0.25mm (a hairs width) from the face of the R/T piston.


Simple, elegant and kinda cool if I do say so myself…

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The Magnet Modification

This mod replaces the trigger spring to make your trigger pull silky smooth and very very light.

It's simple enough, you replace the trigger spring with Rare Earth Magnets. Specifically you need 2 packages of 1/8" Rare Earth Magnets from Radio Shack; there are two magnets to a package and you need a total of four for this mod. I don't recall specifically but I believe each package cost me $1.29 USD. The package part number is 64-1895 and looks like this:



Going back to our High School science days we know that magnets have a North and South pole. North and South attract each other but North and North don't, they repel each other (and subsequently South and South repel each other as well). Since this is replacing a spring that repels the trigger from the frame we are going to install the magnets to do the same thing:



As you see the magnets are double stacked on each side. Stacking them increases the magnetic field (and repulsion from the opposite stack). Super glueing the stack may not be necessary but it will prevent the magnets from throwing each other around inside my trigger! I also super glued the magnets to both the trigger and the spring cup in the right side trigger frame.

I shaved down the nub on the nose of the trigger to be flat but still existent so that I could undo this mod if I didn't like it. This will also help the magnets get closer together when the trigger is pulled which will increase the resistance and assist in keeping my RT in the sweet spot.

Also notice that the nub was shaved at an angle - when the trigger is pulled the magnets will be parallel at their closest point to each other. Is this necessary? Probably not but I'm a bit of a perfectionist...



The end result is a far lighter and smoother trigger pull. It didn't really help me with my RT too much. It turns out that I preferred the stock trigger spring. It has enough tension that it actually makes it easier to keep in the sweet spot.

<another space holder for future updates>

<one more space holder for future updates>

Wtf!!

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In the end we're all just chalk lines on the concrete, drawn only to be to be washed away. For the time that I have been given, I am what I am. ~ Five Finger Death Punch ~