Hard trigger jerk and how to spot it

[Peter]

Let' talk about trigger control, shall we? No doubt one of the most important skills you can develop as a precision shooter.
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Hard trigger jerk just before the shot breaks:
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This error is caused by a sharp, jerky trigger pull. There are several ways how SCATT can help you diagnose this mistake.
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It is clearly visualized on the SCATT trace line as a straight portion of the trace just before the shot (this can be usually spotted in the interval from 0.2 to 0.1 seconds before the shot). In this case, the shot-hole splits away from the hold area and in extreme cases can end up very far from the center (Figure 1).
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Another way to identify the jerky trigger release is the "Average trace speed" graph, look out for a drastic acceleration during the last fraction of a second before the shot - a feature of the SCATT Expert or SCATT Professional software (Figure 2).
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The third option is to compare the S1 and the S2 numbers in the table to the left of the main screen. The S1 represents the average speed of your trace line for each shot, but the S2 shows you the speed in the last 250ms. If the S2 is higher than S1 it means that you've accelerated just before the shot release, which is often a sign of a trigger jerk. Ideally the S2 value should be equal or a bit lower than S1.

 

[ptf18]

Can you tell us where in the Scat program we can find the Average Trace Speed OR S1 and S2?

 

[Peter]

Can you tell us where in the Scat program we can find the Average Trace Speed OR S1 and S2?

Sure thing! Below is a rundown in regards to all three software options:
1) In SCATT Pro S1 and S2 are represented by two columns entitled mm/s and mm/s/250ms respectively

2) In SCATT Expert it's pretty self-evident when it comes to S1/S2
All graphs can be found in the drop-down menu marked as 3 parallel lines in your upper right corner

3) There is no Average Trace Speed graph in SCATT Basic software and the stat-table offers only S1


Hope this was helpful

 

[ptf18]

Peter. Thank you..... but go easy with me. Love the trainer but to be honest I don't have a clue on how to use it other than plotting shots and traces. I've got the SR200-SCATT Professional unit. Seems hard to use. I down loaded a "instruction manual" for it but it doesn't seem to be much help...OR... I'm a dunce.

Anyways...... In the picture you show for the Pro you have an arrow point to SPEED that is in the "task bar". I have that also BUT....its greyed out. I assume that means SPEED is turned off. How do I turn it on?

 

[ptf18]

Peter. I started my Scatt Pro. Went to TOOLS and opened that. Scrolled down to OPTIONS and opened that. Found both mm/s and mm/s/250ms. Closed the TOOLS and found that my SPEED in the TASK BAR is now BLACK and that both of those mm/s show up as columns. I shot a few shots and received numbers in the S1 and S2 columns.

So.... I assume I have "trigger jerking" information available.

How close together should the numbers be? You mention that "Ideally the S2 value should be equal or a bit lower than S1".

I'm using a 2 stage trigger . 1st stage weight is about 3.5# and the 2nd is about 1.25#

I know I jerk the trigger at times. Any suggestions on how to "fix" that?

 

[CharlesD]

ptf18 - this is the post I put on the Scatt Coordination Graph tip thread. It may help.
A rise of the Radial Distance and Coordination traces or S2 in the last 0.25 seconds is most probably due to poor trigger release - either snatching or pulling in a direction that is not directly along the line of the firearm. It will show up on the trace as a relatively long blue section of the trace, often heading away from the mean position of the yellow trace (the immediately preceding 0.75 seconds). If the blue trace tends to head in one direction immediately prior to where it turns red (the point of aim at the instant of firing), that can give a clue as to which way the trigger is being pulled (trace moving to the left indicates trigger being pulled to the right in a rifle and probably (don't know for sure as I've never used Scatt with a pistol) pulled to the left for a pistol).
Ensure that the fleshy part of the finger mid way between the tip and the first joint is where your finger is resting on the trigger, that the finger is in the same vertical position on the trigger every time and that no part of the trigger finger is touching the rifle/pistol at any point other than the trigger itself. The finger tip should be square across the trigger (pointing straight out to the side at a rightangle to the line of the firearm) at the point of trigger release.
Scatt is the perfect tool not only to diagnose trigger faults (snatching or pulling off line), but also to work on finding solutions. Once you have identified a fault - look carefully at the trace and graphs for each shot to see what movements you are getting in that last 0.25 sec (trigger operation period) - you can try things to correct the fault (finger placement, smooth squeeze, etc.). Scatt will tell you whether each thing you try is working - if the problem gets smaller it's working! As Peter has posted elsewhere, you are looking for S2 to be no bigger than S1. Also that the radial distance graph doesn't make any significant change (increase) in that last 0.25 sec on any single shot (should be fairly smooth all through the last second) or when aggregated and averaged over all shots (= the Coordination graph).

 

[ptf18]

Fellows. Thank you all for the follow up info. I knew the Scat can provide alot more diagnostic info IF... I know how to interpret it.

I have attached a 10 shot Scatt file of my latest use of the Trainer. Could someone look it over and perhaps tell me what the Scatt info is telling me please? I hope I can get it attached.

 

[ptf18]

Charles. "Ensure that the fleshy part of the finger mid way between the tip and the first joint is where your finger is resting on the trigger, that the finger is in the same vertical position on the trigger every time and that no part of the trigger finger is touching the rifle/pistol at any point other than the trigger itself. The finger tip should be square across the trigger (pointing straight out to the side at a right angle to the line of the firearm) at the point of trigger release."

Thank you BUT..... I use the AR15 as a Service Rifle in NRA/CMP High power Across the Course shooting "events". Forgive me if what I have to say is redundant for you as I'm not aware of your familiarity of that rifle. The pistol grip of the AR is very small and many of us push our trigger finger far into the "trigger well". This causes our trigger finger to contact the trigger on the "second" pad. Also the trigger weight (2 stage) is at the minimum 4.5 # with the 2nd stage being about 1.5 to 2 # . With our trigger finger this deep the "felt" effort to "trip the trigger" is very low. In addition the pull is more straight back and inline with the gun. BUT this also cause our trigger finger to do what we were long ago (when shooting the M1 and M14) NOT to do and that is "ride the wood" ie contact the "wood" with our trigger finger. Something you mention in your note. Being such is there a "work around" for this? Probably not....

 

[CharlesD]

Fellows. Thank you all for the follow up info. I knew the Scat can provide alot more diagnostic info IF... I know how to interpret it.

I have attached a 10 shot Scatt file of my latest use of the Trainer. Could someone look it over and perhaps tell me what the Scatt info is telling me please? I hope I can get it attached.

ptf18 - If this is shot standing, my apologies for the following comments, which should be ignored. If you are shooting prone, your trace suggests that you are a fairly inexperienced shooter as you are physically holding the aim and using your muscles to bring the rifle onto aim rather than being relaxed, with your natural point of aim (NPA) correctly aligned with the target. The technique to strive for is a prone position where the rifle is held up by the sling and your body, arms and supporting hand are completely relaxed (floppy). If your position is correct (left hand, wrist, forearm, elbow, shoulder, left side of the body and left leg are all in line) and the sling tension is correct, you should be able to take your left hand off the rifle, lift your right elbow, relax your left arm and hand (try to drop the rifle) and the rifle still stays pointing horizontally and does not try to fall down, or to the left (elbow too far in) or right (elbow too far out). In this position, the right hand can be put on the pistol grip before dropping the right elbow to the ground where it only needs to support its own weight. Unless it is very windy, you should not be taking any significant weight of the rifle on your right elbow. Once this position has been achieved, where you are lying totally relaxed and the rifle is holding itself steady, close your eyes, breathe in then out to a naturally exhaled state (not held part in nor forced out) and, keeping your eyes closed, 'feel' the relaxed aim and then open your eyes and see where the sights are pointing. (If your head is not in a position to see the foresight in the middle of the rearsight, you need to adjust the cheekpiece until it is.) Where the sights are pointing is your NPA - where the rifle wants to point. You need to pivot round your left elbow, shuffling your hips left, right, forwards or backwards to move your NPA until, when naturally exhaled, your NPA is right in the middle of the target. In this position, as you breathe in your foresight will dip below the target at 6-7 o'clock and as you breathe out again, the foresight will rise and, when you are naturally exhaled, it should stop with the aiming mark in the middle of your foresight. Your body should be completely relaxed and you are effectively aiming with your diaphragm as you breathe. As the foresight comes up onto the target, take up the first pressure. When it stops, check that the alignment is indeed good, and squeeze the shot off. The shot should be released within 3-6 seconds of coming on aim, but if the aim is not good, simply take another breath. The next aim will almost certainly be better, but if not, just take another breath. The image below shows what yo are trying to achieve. The aim comes in from 6-7 o'clock then stops almost dead until the shot is released, with the follow-through (red) in much the same place for at least a second.

A good, relaxed position with a straight squeeze on the trigger will get you a long way towards this sort of trace.

 

[CharlesD]

Charles. "Ensure that the fleshy part of the finger mid way between the tip and the first joint is where your finger is resting on the trigger, that the finger is in the same vertical position on the trigger every time and that no part of the trigger finger is touching the rifle/pistol at any point other than the trigger itself. The finger tip should be square across the trigger (pointing straight out to the side at a right angle to the line of the firearm) at the point of trigger release."

Thank you BUT..... I use the AR15 as a Service Rifle in NRA/CMP High power Across the Course shooting "events". Forgive me if what I have to say is redundant for you as I'm not aware of your familiarity of that rifle. The pistol grip of the AR is very small and many of us push our trigger finger far into the "trigger well". This causes our trigger finger to contact the trigger on the "second" pad. Also the trigger weight (2 stage) is at the minimum 4.5 # with the 2nd stage being about 1.5 to 2 # . With our trigger finger this deep the "felt" effort to "trip the trigger" is very low. In addition the pull is more straight back and inline with the gun. BUT this also cause our trigger finger to do what we were long ago (when shooting the M1 and M14) NOT to do and that is "ride the wood" ie contact the "wood" with our trigger finger. Something you mention in your note. Being such is there a "work around" for this? Probably not....

UK fullbore trigger pressure requirement is 1.5kg (3.3 lb). First pad works fine with this and helps to ensure the trigger finger doesn't ride the wood. Nevertheless, any trigger action where the finger is at right angles across the trigger and stays like that through the final stage trigger pull should work, provided the moving parts of the finger are not touching the rifle other than on the trigger. Scatt shows if the trigger pull is not straight as the blue trace moves significantly away from the last second average aim point, often in the same direction. S2 will probably also be larger than S1.

 

[ptf18]

Charles/Petter. Thank you ever so much for your reply.... Please forgive me for NOT mentioning that the attachment I posted was conducted from the STANDING/OFFHAND position.

How does this change they diagnostics your provided?

As for the trigger finger location. The "issue" as I see it, is that the construction of the full-bore rifle is vastly different than the AR platform. Being that the AR features more of a "pistol" grip than the "tradition" wooden stocked rifles many "prone" shooters are using. In addition the AR "pistol" grip is "smaller" in size than what is ideal for many shooters hand size.

I don't know how the difference in construction of the grip area effects the SCATT results even when the outcome of "the shot" is in its "ideal" location. Hope that makes sense. Perhaps looking at "pistol" shoters SCATT results would yield a "clue".

Thank you so much for your help.

 

[CharlesD]

ptf18 - I'm not a standing shooter, so am not well placed to comment on your Scatt traces. My 'basic principles' post above may be of help to less experienced prone shooters, but I will leave advice on what your traces mean to people who are experienced standing shooters. I believe the main principles still apply, though: Establish a stable position that is as relaxed as possible and adjust orientation to ensure that the NPA is aligned with the aiming mark. When the aim is good, squeeze the trigger straight back. Scatt will show what is happening - monitor the blue section of the trace to see how good the trigger release is.

 

[Ramon OP]

Anyways...... In the picture you show for the Pro you have an arrow point to SPEED that is in the "task bar". I have that also BUT....its greyed out. I assume that means SPEED is turned off. How do I turn it on?

It probably is grey and unclickable because you are in your sighting shots. The moment you go into Match you will be able to look at it.

 

[Irritant]

I have not read all the above so maybe this has already been said.
The heavier the trigger the tighter you should grip. this allows vastly better control. A good test for this is to take a Garand out for a shoot and if you can make it double you have good trigger control. Doing this with a Garand is actually pretty easy.

 

[CharlesD]

I have not read all the above so maybe this has already been said.
The heavier the trigger the tighter you should grip. this allows vastly better control. A good test for this is to take a Garand out for a shoot and if you can make it double you have good trigger control. Doing this with a Garand is actually pretty easy.

What do you mean by 'make it double'? Is that get it to fire two shots in semi-auto mode? (Presumably with two squeezes of the trigger in quick succession?) Note that in the UK (and most/all European countries?) semi-auto rifles above .22" are prohibited, so we don't get a chance to play with them.
In the UK the minimum trigger pressure for fullbore rifles is 1.5kg, so probably similar to your Garand. You don't need a tight grip, just good trigger technique that squeezes progressively along the line of the rifle. If you have a pistol grip or a thumbhole stock (as opposed to having your thumb over the top of the butt), a 'pincer' squeeze between the tip of the finger on the trigger and the part of the thumb in line with the trigger, with the same pressure on both points, will produce a straight trigger action. Not so easy if the thumb is on top of the stock as the pull on the trigger using this technique will tend to be upward rather than straight back. In that case, the other fingers tend to have to come into play to keep the trigger finger moving straight along the line of the rifle.
Scatt is very good at showing whether the trigger action is straight back or off to one side (or up or down). The blue part of the trace is the bit to look at closely - if it tends frequently/always to move in one direction from where the yellow stops to where the red starts, the trigger pull is not straight. This also shows up in the red and blue traces on the 'Distance' tab. Ideally the traces should both be fairly flat as they go through t=0. If one or both of the traces tends to rise or fall significantly in the 0.1-0.2 seconds either side of t=0 your trigger action is poor and needs attention. If the Distance traces show no disturbance through t=0 and the target trace shows the end of the yellow trace and the start of the red trace to be fairly close and in various directions from each other, your trigger release is good.

 

[Irritant]

Hi Charles,

Thanks for setting me straight on this.
I have shot the Imperial a number of times and I know my way around this stuff. I must admit I am not nearly as verbose as you.

 

[DavZee]

Slipping a tiny O- ring onto your trigger can help in finding the same position every time.