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Member Since 08 Jun 2017
Offline Last Active Sep 12 2018 10:08 AM

Topics I've Started

comparing chronograph results

18 June 2017 - 04:48 PM

Hello! This is my first post - I couldn't figure out where it belongs, so my apologies if it shouldn't be in general nerf. I'm just getting into the hobby in the past few months, and I was lucky enough to pickup one of Captain Slug's Caliburn kits. I recently completed the blaster and ran it through the chronograph today. Honestly I'm not into going to wars, but rather the statistics around different blaster configurations really fascinate me (in addition to pew-pewing cups with my kids around the house / backyard). I enjoy data collection and visualization, so I started thinking of some interesting studies that would generate data sets that would make for some cool plots. I've amassed a relatively comprehensive set of readings from a variety of blaster configurations focused mostly on Retaliators (and I figured it would be cool to throw the Caliburn into the mix), which raised the question - how does everyone compare chronograph readings when we don't have a method for baselining / comparing standardized results? 


Here's what I have for a series of comparisons of 100 shots with each blaster:


Attached File  springerFPS.png   53.94KB   14 downloads


Each plot represents the population of readings in light gray dots. The minimum and maximum readings for the population are reported as horizontal bars and labeled "max" and "min". The average for the population is the large horizontal bar labeled with the largest font. The white circle is the median value. The two smaller horizontal bars are the 25th and 75th percentile values. The "+/-" values reported as part of the FPS value are the 95th percentile confidence intervals for the population, meaning you would expect 95 of 100 shots to fall within that range (~2 standard deviations) of the average. I can provide the full data sets for those interested.


I'm really impressed with the consistency of the Caliburn. Note how awesome and symmetrical that population plot looks - where the min, 25th, 50th, average, 75th and max fall where we'd expect. You see more variation in the results from my retaliator studies (these were all within 1 foot of the chronograph). 


So on to my problem.


My chronograph, a Caldwell Ballistic Precision Chronograph, *seems* to record fps readings consistently lower than what is typically reported in the hobby. My baseline figures from a stock retaliator come in at about 54 fps, 15 to 20 fps lower than what seem to be commonly accepted hobby standards. I had a feeling my results were consistently low for the Retaliator spring / kit configurations I was testing. This suspicion seems to be playing out with my Caliburn numbers - my chronograph is reporting ~172 fps, is ~20% lower than what I expected. This combined with the ~25% lower readings on my baseline Retaliator makes me suspect my chronograph is reporting low figures.


I picked up the Caldwell at a good sale price, but I'm thinking I need a different chronograph. Has anyone else seen consistently low results from Caldwell's? I see quite a few other folks using Competition Electronics units - I'm guessing there's a reason :) From what I've read these units are factory calibrated, but it doesn't seem like there is a field calibration method. I fully admit I'm new to this, so I may have missed something in my searching. Hence my post.


Anyhow given how accurate some of these upgraded blasters are I've been looking into conducting FPS and accuracy studies at a variety of ranges for a blaster. I've done one analysis on a Retaliator, but before I dig in and produce these studies on more configurations I want to get a chronograph setup that I can trust. Right now, my results are OK for comparative testing on my unit, but I'd like to have more confidence in the results I'm producing when compared to other folks. This is the type of study I had in mind:


Attached File  springerRETaccuracyFPS.png   61.06KB   13 downloads


I'm measuring accuracy as a function of how many readings I can get from the chronograph at a specific distance. In this plot you see the population of readings from the chronograph and the associated statistics in the upper portion of the plot for each distance (x-axis). Below the FPS plots is a figure of reading count. You can see the number of readings drop off as you move further to the right which is a greater distance from the chronograph. The data collection on these is fairly intensive (100 shots from each distance) so I want to have confidence in the chronograph before proceeding with a lot more tests.


I'd appreciate any tips anyone has on chronographs, as well as recommended studies where there may be a need within the hobby. Personally the accuracy at various range studies seem intriguing, which is where that second plot is going. Given how accurate some of these blasters are (were I can get a significant population at a decent distance), using this "how many readings do I get at a distance?" seemed like a good start.


Thanks in advance!