The Goal

The Goal

Friday, 5 June 2015

Interpreting SCATT results, Part 1 - Traces

To get the most out of a SCATT, it is valuable to learn how to interpret the various bits of information that it provides. The two key approaches that I have found useful when using a SCATT to analyse technique are interpretation the trace itself, and numerical analysis of some of the values that SCATT provides. These two approaches appear to be useful for different things and under different circumstances. Traces are the most immediate way of using your shooter training system to help you improve.

I find the traces themselves to be most useful in identifying and diagnosing gross or intermittent errors in technique; however it should be noted that not all errors always show up on SCATT (flinch or snatch being one of them) so it shouldn't be taken as read that a shooter with a perfect SCATT trace doesn't have any other issues. Trace analysis is less useful in refinement of an already good technique or in comparing two positions, techniques or items of equipment.

Interpretation of Traces
SCATTs and other shooter training systems record where the rifle is pointing through the shot sequence as a coloured line on the target diagram. This is generally called the trace.

The trace is made up of the green, yellow, blue/grey and red lines superimposed over the target. The shot is represented by the purple circle. Image has been edited to reduce the amount of whitespace.
The trace can be replayed by hitting the "Replay" button in the top left of the shot list pane. This will show the sequence of colours. The default settings for SCATT are as follows*:
  1. Start of trace until last 1 second - GREEN
  2. Last 1 sec - YELLOW
  3. Last 0.2 sec - BLUE/GREY
  4. Follow-through - RED
This is important to understand as it will give you information on when an error is occurring during the shot sequence.

Big / Obvious Things

Poor Hold - In the image below you can see that the trace is just really big. This is the kind of thing you see with beginners. Seeing it is easy, knowing what to do about it is harder, as it can be a lot of things. Look at jacket fit, sling tension and arm tension for starters.

In out, in out, shake it all about.

Pointing Errors - If you don't point the thing in the middle then the shot doesn't go there. If the trace length and the shot release are OK, but the shot is out of the group then you probably just pointed the rifle badly. Make sure that you're centring the target correctly in the foresight and the foresight in the rearsight. If you think you're OK on these fronts and you've not had one done recently, go get an eye test. I used to use Stewards of Bisley and always found them perfectly acceptable, but swapped to Gary Alexander a few years ago as it was more convenient and the craic is better.

A really nice group spoiled by one high left shot. From the trace it was clear that it was just aimed in the wrong place; the trace length, shot release and shape of the trace were all fine.

Snatch / Twitch / Flinch - The movement of the rifle sped up just as the shot broke and the shot got "flung" quite a way from the centre of the hold. This sudden, rapid motion is usually caused by flinch, snatch, a muscular twitch. The shooter needs to work on not anticipating the shot.

Whoops, that one got away from me. Aim and hold aren't bad though.

Wander - If the rifle consistently wanders left or right as you pull the trigger, then you're probably not pulling it straight or your NPA isn't aligned with the centre of the target. To test if it's trigger pull, take the first stage of the trigger and release it while watching the screen. If the rifle moves back and forth, you're not pulling the trigger straight.

The aim drifts in from the far upper left quadrant of the bullseye. This was the first in a string of otherwise good shots centred high and left, so could have been skew-whiff trigger pull.

Littler Things

Heartbeats - Heartbeats show up as loops or kinks in the trace at regular intervals. Don't worry about these as there's pretty much nothing you can do about them; although you will find that with practice you can lower your heartbeat when you're about to shoot. Shooting at the natural respiratory pause helps also.

The little loops with the blue rings (added by me using paint) around them are the result of heartbeats.

Kinks - If your trace is kinky or spiky then there's unwanted muscle tension, which probably isn't helping. Make sure that you're relaxing your left arm and right shoulder completely. The rifle should naturally want to point at the middle of the target (see The Magic Bullet Magnet Theory) so there should be no need to muscle it into position. If you're also dropping the occasional shot low, then you may be holding the rifle up on the target. Check your sling is tight enough, your sling isn't slipping down your left arm, and that you're jacket is a tight enough fit.

The hold is good and the result excellent, but the spikes that can be seen in the green trace rising up towards the bullseye as the shooter exhales are the result of muscular tension in the left upper arm or the right shoulder. 

Spikes - Every so often something really odd will happen and you'll get a massively flung shot. The trace may look OK, but the purple splotch may be miles away from the trace; or the trace has an enormous spike in it and the shot is well out in the magpie, outer or worse. There seem to be two causes for this: the most likely one is interference from lighting or strong heat source. Occasionally though, the plastic grommet which holds the lens in the front of the optical sensor can work loose. Once you've eliminated lighting and strong heat sources as an issue, the easiest way to test for this is to clamp the rifle in a workbench and fire a couple of shots at the target very carefully.

Massive, unexplained spike. This may be the result of a really bad shot or infrared lighting interference, but occasionally can be the result of the plastic grommet which holds the lens in place in the optical sensor loosening and allowing the lens to move. Please Note - Image doctored to show the effect, as I couldn't find one in my SCATT files.

Finally, some caveats: there are several schools of thought on how to do this and these are only my ideas and what I have found to be useful. Other people think differently, so it's really worth reading around the subject; however there doesn't seem to be a huge amount available. I am still developing my expertise, so please don't think of this article as the be-all or the end-all; it's really just a primer.

*These can be modified through the "shot parameters" and "options" entries in the "Tools" menu. If something looks a little weird then it may be worth checking these haven't been modified.

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