Hey guys, here's my latest issue; I'm sure many have run into this same issue when using sabots or projectiles with wadding behind them.
It goes like this:
I have a Chrony Beta Master chronograph which uses typical twin optic sensors like many. I try to put the chrono far enough away to achieve some separation time between wad/gas seal and bullet or sabot and bullet, but not so far as to have the sabot stray off and strike the unit. Anyways, what happens sometimes is that I get a really high velocity reading, for example 500fps faster than the load is capable of, or in other instances I simply get an error message. I can't be for sure about the error cause without knowing if something is actually detected by the sensors, but I have an idea of why high velocity readings might occur. Let's pretend that the bullet is reaching the first sensor plane with a gas seal following behind it (I have watched my own videos where I have shot targets at 15 yards or so and have witnessed the gas seal bouncing off the target very close to where the bullet impacted). In this theoretical scenario, maybe the bullet passes the first sensor plane and is or isn't detected (not sure how the logic programmed into the unit uses the sensor data) and then while the bullet is in between the two optical sensors the gas seal is detected by the first sensor plane, restarting the timing sequence. Next the bullet reaches the second sensor plane to be detected, the gas seal possibly isn't detected at this plane, and the time frame between detections is thus shorter than if only one object had passed between sensors. Obviously the shortened timing creates a higher velocity reading and voila, incorrect bullet velocity is reported. That's a theory I have which may create the problem, at least.
If the logic of the chronograph calculation only allowed 1 event or object passing the first sensor to begin the timing, then "threw out" a second detection immediately following at the first plane, taking the next detection at plane 2 as the prominent figure for the calculation of velocity, it seems this type of error could not occur. If they want to make their chrono suitable for fully-automatic fire or something (let's see how long it takes for the chrono to get hit!), at least have some sort of non-detection delay built in of 15ms or so--right?
The problem for me currently is, no mfg is posting the sensor logic their chrono uses for final velocity calculation in the unit specs (not like I actually expect this from them). My fastest method to getting help would be to email each mfg of a chrono and possibly getting a generic reply from someone who may not actually know (like, "Sure it will work fine with sabots!"), or asking the many possible shooters here with actual chrono experiences to note upon.
My immediate thought was, well duh, I'll just use a magneto chrono to solve the problem! Then I quickly remembered that the rifle being tested will absolutely rip any attached device off the barrel. It has the recoil of firing 12x 30-06s from a typical sporter weight rifle at the same time (this is not an exaggeration or joke--the rifle reaches >45fps recoil velocity in the time it takes the bullet to travel the barrel length).
A magneto chrono is basically out of the question, then.
I now aim my faith at the forum members for possible help choosing a better chrono or method to advance upon.
Thanks for any help, it is much appreciated.
Happy shooting!
It goes like this:
I have a Chrony Beta Master chronograph which uses typical twin optic sensors like many. I try to put the chrono far enough away to achieve some separation time between wad/gas seal and bullet or sabot and bullet, but not so far as to have the sabot stray off and strike the unit. Anyways, what happens sometimes is that I get a really high velocity reading, for example 500fps faster than the load is capable of, or in other instances I simply get an error message. I can't be for sure about the error cause without knowing if something is actually detected by the sensors, but I have an idea of why high velocity readings might occur. Let's pretend that the bullet is reaching the first sensor plane with a gas seal following behind it (I have watched my own videos where I have shot targets at 15 yards or so and have witnessed the gas seal bouncing off the target very close to where the bullet impacted). In this theoretical scenario, maybe the bullet passes the first sensor plane and is or isn't detected (not sure how the logic programmed into the unit uses the sensor data) and then while the bullet is in between the two optical sensors the gas seal is detected by the first sensor plane, restarting the timing sequence. Next the bullet reaches the second sensor plane to be detected, the gas seal possibly isn't detected at this plane, and the time frame between detections is thus shorter than if only one object had passed between sensors. Obviously the shortened timing creates a higher velocity reading and voila, incorrect bullet velocity is reported. That's a theory I have which may create the problem, at least.
If the logic of the chronograph calculation only allowed 1 event or object passing the first sensor to begin the timing, then "threw out" a second detection immediately following at the first plane, taking the next detection at plane 2 as the prominent figure for the calculation of velocity, it seems this type of error could not occur. If they want to make their chrono suitable for fully-automatic fire or something (let's see how long it takes for the chrono to get hit!), at least have some sort of non-detection delay built in of 15ms or so--right?
The problem for me currently is, no mfg is posting the sensor logic their chrono uses for final velocity calculation in the unit specs (not like I actually expect this from them). My fastest method to getting help would be to email each mfg of a chrono and possibly getting a generic reply from someone who may not actually know (like, "Sure it will work fine with sabots!"), or asking the many possible shooters here with actual chrono experiences to note upon.
My immediate thought was, well duh, I'll just use a magneto chrono to solve the problem! Then I quickly remembered that the rifle being tested will absolutely rip any attached device off the barrel. It has the recoil of firing 12x 30-06s from a typical sporter weight rifle at the same time (this is not an exaggeration or joke--the rifle reaches >45fps recoil velocity in the time it takes the bullet to travel the barrel length).
A magneto chrono is basically out of the question, then.
I now aim my faith at the forum members for possible help choosing a better chrono or method to advance upon.
Thanks for any help, it is much appreciated.
Happy shooting!
