Cheating at the Chrono

[BritinUSA]

I think really the only way to coming close to "solving" this problem is for USPSA to come up with a required chrono set-up (kinda like the classifiers... here's what you MUST have, and how it MUST be set up).

I agree in principle but here's the problem. I have been to matches where they use the CED Chrono and they had two of them set up in series. So each bullet gave two readings. There was no consistency with the two readings, one would be high the other low and vice-versa. I cannot find any indication anywhere of the claimed accuracy of these units. Measuring in a lab is not the same as using at a range, how do we know what the margin of error is ?

Measuring a bullet speed by passing between two sensors is problematic, if the round does not go across the sensors at EXACTLY 90 degrees then there will be a discrepancy in the reported speed. It doesn't take much, some kind of doppler radar would probably work better or failing that a way to calibrate the chrono at the range using a known velocity, such as a linear motor that is driven at a known speed across the sensors of the chrono. You know exactly the speed of the motor and any deviation of the chrono reading can be adjusted with a calculator.

[BlackBuzzard]

I expect these folks .... http://www.weibel.dk/Default.aspx ........ might make a highly accurate doppler radar.

And chono makers equipment that we all have and use, KNOW how accurate their stuff is but decline to say anything (that's a little spooky to me) .

Personally I'm going with a +/- 4 percent figure at the chono stage. And I feel for those that get penalized when close to the edge since there is a 50% chance their ammo really does make PF.

This topic would make for a fine FRONT SIGHT article (anyone listening?), comparing off the shelf chronos with gold standard, callibrated, and certified equipment. Previously penalized shooters might be vindicated! Prior match awards get recinded and awarded to rightfull recipients.

But then ad space purchased in said publication by chrono-makers might drop off a little thereafter, eh?

BB

[Dan Burwell]

I agree in principle but here's the problem. I have been to matches where they use the CED Chrono and they had two of them set up in series. So each bullet gave two readings. There was no consistency with the two readings, one would be high the other low and vice-versa. I cannot find any indication anywhere of the claimed accuracy of these units. Measuring in a lab is not the same as using at a range, how do we know what the margin of error is ?

I have seen this several times. It is hard to believe they can be so screwed up. I mean, I get my reading being different at home, but to sit there and watch CED IR's in the 'coffin" go back and forth it just doesn't seem right when we are also asking for overlays cause that hit looks like it might have broken the perf.

[kevin c]

I think we're getting stuck on wanting absolute precision in a situation where it isn't possible.

PF is the average of the measured velocities of three rounds times the weight of a pulled bullet. A problem here is that the neither the actual velocity nor the real bullet weight is likely to be identical from round to round. That means actual PF varies with each round shot. All you can do is get an approximation of the PF for each shooter's ammo.

Then there's the problem of variation the measuring devices, which is what the preceding posts are expressing reservations over. The most any instrument can do is give a number close to or equal to the measurement we want to have. The number you get is only a close (or not so close) approximation, and that's true for every single shot measured. This is also true for measuring the weight of the bullet.

Then there's variability in the test conditions that will change the actual velocity or how the instrument reads it. The rounds are not truly identical, because components and loading technique introduce variables. The light/weather/altitude vary. Cripes, even your own gun changes from shot to shot (my first round from a cold barrel is always the slowest with my loads).

All that to say the PF is an approximate measurement, due to the nature of the measuring devices, the conditions tested under, and the variation in the ammunition. The problem comes from the sport's need to use some absolute number as the threshold for power. There isn't anyway I can see of making a "line in the sand" an approximation. The sport uses a threshold number, and acknowleges that measuring for that number is inexact by allowing you the best three of six or seven rounds and the better of two bullet weights.

Don't want to go minor/subminor? Don't crowd the PF threshold.

(I still think using steel is a viable alternative - it may not be more "exact" but the whole thrust of recent posts is that chrono'ing isn't that either, and the steel makes it pretty hard to game it (OK, CHEAT) with special ammo come the chrono stage. Even better - eliminate the chrono and have another stage in the match.)

Edited June 11, 2009 by kevin c

[71Commander]

At Area 5 last year, I had a 172 PF W/ my 625. I worked this load up using my own chrono. Didn't have a problem at Mi. sectional either.

Shot A6 this year, without making any changes. It went down to my last round. Ended up wwith a 165.8 PF.

I hate chrono.

[nphd2000]

After reading this thread I start to wonder, when we reload do we weigh every bullet and adjust our powder charge to the weight? For that matter, how accurate is our powder drop, do we weigh each drop.....what about the scale we use to weigh the bullet ...or to weigh the powder charge.....what is the variation in primers, powder variation batch to batch....Oh I have a headache.

On a serious note, I have been witness to a chrono stage or two, and I have yet to hear from one of the shooters that we have seen on TV walk away from the chrono and comment about the in-accuracy. Most usually say "just where I thought it would be".

[9146gt]

Do we need a chrono rule?

Projectile must pass through the target and backer and knock down all other targets.

Thanks

Tom

[ac4wordplay]

I love the BE forum! Many of the discussions here are both fascinating and educational.

I haven't personally had an issue (yet?) with the chronograph stages that I've been through and don't find myself worrying about the topic, but I've enjoyed the issues pointed out in this thread and found many of them thought provoking.

Correct me if/where I am wrong:

- Weight (mass) is verifiable, and tools that measure mass (scales) are normally easy and quick to calibrate (or at very least, confirm calibration). Faulty tools (scales) can be identified and removed from the process. An object (bullet, or powder) can be the subject of multiple attempts to measure mass by the same unique tool (scale) or similar tools (alternate scales).

- Speed (velocity) isn't verifiable in the same sense, and tools that measure velocity (chronographs) aren't normally easy nor quick to calibrate (can this be done by the end user at all?). Can faulty tools (chronos) be easily identified (short of "it won't turn on", or readings that are considerably over/under, or the official match chrono ammo average is significantly different on different days) and therefor promptly removed from the process? I've seen (and heard of) enough problems that this seems doubtful. An object (bullet) can be the subject of a few (I haven't heard of more than two chronos inline) attempts to measure velocity by non-unique chronos, but multiple attempts to measure the velocity of a single (unique) bullet by a single (unique) chrono are not possible (to my knowledge).

Simply put:

- Pull a bullet and measure the mass of the bullet. If someone thinks the scale's reading (mass of the bullet) is NOT the actual mass of the bullet, then the scale can be calibrated such that both parties are satisfied or the bullet's mass can be measured on an alternate scale that satisfies both parties. Bullet mass is now "measured" and agreed upon. Bullet mass issue settled.

- Fire a bullet over/through a chrono and measure the velocity. If someone thinks the chrono's reading (velocity of the bullet) is NOT the actual velocity of the bullet... tough luck - that bullet is gone. Maybe the lot of ammo is highly consistent and the next bullet's velocity is the same (for our purposes) as the first, BUT... there isn't a recognized calibration method. (Firing factory ammo of advertised "X" velocity isn't a method of true calibration). Bullet velocity can be chrono'd and averaged, but these can still be argued as inaccurate approximations. Without calibration, chrono velocity reading is suspect and won't be agreed upon. Bullet velocity issue NOT settled.

--> Without a valid calibration method that can satisfy both parties, it seems that chrono-based velocity approximations will remain contentious. Having the same make/model chronos inline and offering wildly different readings (which I have witnessed) greatly reduces competitor confidence.

I agree with the "don't crowd the threshold" statement, and I understand the frustration one would feel if their "tried and true" load chrono'd significantly lower (and didn't make desired PF) at a major match. I have no idea how to solve the chrono issue, but I look forward to the discussion.

just my thoughts

ac

[Carmoney]

I went minor at the very first major USPSA match I ever shot! So I simply adjusted my load to run about 174 p.f. and have never had a problem making major, anywhere. And I shoot a lot of big matches.

[Alan Meek]

I am interested in the configuration of the Chrono boxes.

How are they built?

Are the screens interlaced or set end to end.

Are the screens aligned?

I will post pics of the chrono box I just built for the VA MD Section and my personal use. this evening.

I tested the box with my airsoft and the readings were generally less tan 1fps different I even moved the chronos between the skyscreen sets and the readings stayed pretty much the same.

I will test the chronos and box this Fri prior to the start of the VA MD Section and will update with those actual results.

Alan

[pskys2]

Funny thing is the only time I notice Recoil is during practice.

Even with 185 PF loads in years past, I never noticed it during a COF. Must be the mind is so full of "Oh S*!t" thoughts that the recoil is low on the list.

Load for +10PF unless your loads are having wild ES or inverse temps, like WST then you might have to go even more. It's just not worth the anguish to cut it too close.

[pjb45]

I have recipe for my match ammo. I use different brass but the primers, bullets, powder, and amount are the same. Over several A2 and National matches, my ammo has chrono'd pretty close to the same each time. The major difference occurred at last year's Nationals, where the outside temp was different and I was 167 one day and 171 the next.

The chrono setup for A2 and Nationals is very similar.

I know when I use a friend's chrono outside the velocity is much faster in the daylight. My other friend's Oehler chrono always comes very close to the A2 and National results. There is always going to be variability during each chrono experience because each piece of ammo has variability built into the process. The average of three plus others is a very good way to get a decent average velocity.

I approve of the idea of using a scale and chrono's with a fixed light source. It does eliminate some of the variances produced by sunlight. My results over several years have shown to be very consistent. But then, I try to keep my ammo in the 170 PF range.

Additionally, I truly believe some competitors have 'chrono' ammo in their bag and lower powered stage ammo. Last year, I shot a match with a competitor whose first stage when the ammo was collected, has appropriate muzzle flip. Then every stage after, there was no muzzle flip whatsoever. Maybe his hands and wrist got stronger. But I was standing next to two RO who quietly question if he was shooting minor and looked at the squad list. They did not say anything to the competitor. I have seen this occur in more than one match.

I am all in favor of doing random collection of ammo during the match. A2 did it one year I think.

[CHA-LEE]

If there is a known chrono accuracy variance of +/- 3% then just add that compliance to the PF requirement. Meaning the minimum for Major would be 165 - 3% (160 – 165). If you are willing to gamble and load your rounds down to 160 PF and end up below that then that’s your fault. We all know that you can barely feel a difference in 5 PF points so there would be no reason to go blow 165 intentionally.

People that are going to cheat will not be hovering so close to the minimum PF anyway. The rare 1% of the cheaters out there are using rounds that are well below the PF minimums and that will be boldly obvious when their rounds are run through the chrono.

I think it’s a very raw deal when a shooter goes to a match with ammo that he has tested at home and knows it makes major only to end up with a 164 PF and be bumped into Minor. This shooter isn’t cheating intentionally. He has just been bitten by the excessively stringent Major PF requirement that is measured with inherently inaccurate equipment.

I vote for Minimum PF Ranged that correlate to an acceptable measurement variance that does exist with today’s optical chronographs. Such as 160 - 165 PF for Major and 121 – 125 for Minor.

Since we all know that there is a very small subset of shooters that are actually trying to cheat on the PF intentionally, then just perform a random drawing of 2 shooters from each Squad. Then simply have the Chrono team instruct each stages RO to capture X amount of rounds from said competitors after their stage run. For example, you could have a strategy of capturing ammo from those two competitors on the third stage cycle of the day. Put the ammo in a sealable baggie/box and then give it to the Chrono team. Then those few shooters that had their ammo collected could report to the Chrono “Stage” at a predetermined time when the normal stages are not being run. That way everyone gets chronoed at the same time of day/light and its all done in a minimal amount of time.

It does not make sense to push every single shooter through the chrono process during a match as it is a huge waste of time and resources when you are trying to “Find” a very small subset of cheaters that may or may not exist at the match.

At least doing it this way will minimize the wasted time and drama of chronoing everyone at the match. It will also give the average shooter, who isn’t intentionally trying to cheat the system, some slack if his ammo misses the minimum PF mark by three percent or less.

[George Jones]

No matter where you draw the line on PF, regardless of whether you apply a "variance" or not, someone out there will fail by pushing too close to the new "limit".

All these mental gymnastics accomplish nothing except to generate conversation (not particularly a bad thing).

The numbers are what they are. We used to have a 175 Major PF and shooters failed then. It was lowered to 165 and shooters fail now. Drop it some more and shooters will still fail.

As long as the chrono crew really knows what they're doing, it's more human nature than chrono problems .

[ammowaster]

No matter where you draw the line on PF, regardless of whether you apply a "variance" or not, someone out there will fail by pushing too close to the new "limit".

I agree. No matter where they move the limit people will push it.

[BritinUSA]

I thought I would check out the CED web-site to see if it has any information about chronographs in general... It did. It said this...

Chronograph Results and variables that effect readings…….

The spread between the existing brands of chronographs on the market today is aprx. 8.0%. This has a lot to do with the quality of the sensors & components used, the distance in which the sensors are spaced apart, and the firmware design of the product itself.

Link to web-page is here

I told you... it's like shooting bullets into the Twilight Zone.

[Nik Habicht]

I told you... it's like shooting bullets into the Twilight Zone.

I don't think I agree. My experience is pretty short --- compared to yours --- but I've been through chrono at least 25 times in 25 different matches. I've never been surprised by the reading --- but I also haven't dealt with huge elevation changes.....

[Skizeks]

It is what it is! If you want it changed you have to go the right source.

This forum, as great as it is, is not the right place. I think we stoped

hearing new things a couple pages ago.

Try NROI or USPSA here you will find the people that can change it.

Wierd thing but before I started shooting ISPC I think they did use some

sort of fulcrum. Interesting to find out why it was changed?

IMO Duane

[mountaincoulee]

.....

Wierd thing but before I started shooting ISPC I think they did use some

sort of fulcrum. Interesting to find out why it was changed?

IMO Duane

Duane your fulcrum reminded me on an 1850s treatise on Naval Artillery ballistics I read a few years ago.

The author, a Royal Navy officer, stated that in the 1700s the French developped

a ballistic pendulum with which they measured the power of smoothbore roundshot, i.e. 12pdr, 24pdr, 36pdr cannon. The cannon would be fired while suspended in a cradle and its rearward motion measured. They would then calculate the corresponding muzzle energy.

The RN Officer also reported that velocity was measured by firing roundshot through a large open-ended 10m-long cylinder. The cylinder was geared to rotate at a known RPM. The shot would cut a hole into the papered-over ends, said papers being imprinted with 360 degree radial markings. The papers were in perfect degree alignment with each other, so the shot would enter at a certain degree point and exit at another. Velocity would be calculated accordingly.

All that back in the 18th Century.

Edited June 19, 2009 by mountaincoulee

[buddy_fuentes]

.....

Wierd thing but before I started shooting ISPC I think they did use some

sort of fulcrum. Interesting to find out why it was changed?

IMO Duane

Duane your fulcrum reminded me on an 1850s treatise on Naval Artillery ballistics I read a few years ago.

The author, a Royal Navy officer, stated that in the 1700s the French developped

a ballistic pendulum with which they measured the power of smoothbore roundshot, i.e. 12pdr, 24pdr, 36pdr cannon. The cannon would be fired while suspended in a cradle and its rearward motion measured. They would then calculate the corresponding muzzle energy.

The RN Officer also reported that velocity was measured by firing roundshot through a large open-ended 10m-long cylinder. The cylinder was geared to rotate at a known RPM. The shot would cut a hole into the papered-over ends, said papers being imprinted with 360 degree radial markings. The papers were in perfect degree alignment with each other, so the shot would enter at a certain degree point and exit at another. Velocity would be calculated accordingly.All that back in the 18th Century.

Heck, I have trouble balancing my check book . I'll stick to our current methods of measuring.

Buddy

[geezer-lock]

Out on the stages we seem to agree that if the shooting challenge is consistent then everyone has an equal opportunity to succeed. You control the outcome for the most part. The current chronograph setup at the nationals (and similar setups at Area matches) seems to be as consistent as can reasonably be expected given the equipment and the cost. We all have the opportunity to succeed in such a case. You control the outcome for the most part.

DVC

David C