[Shawn Knight]

Yesterday I went to chrono my 9mm minor load and I had some very high readings. I have a Shooting Chrony Betta Master edition and the load I was using was a very common load in 9mm.

147 Zeros seated to 1.130
3.3gr Tightgroup
mixed brass
Win small rifle primers(only to keep costs down. 1 primer for 4 different calibers)

Velocity was kind of high....

975fps-1000fps.

Now just to try something else I shot my buddies open gun and tried his 180PF 38SC load. It was coming out to be 194PF on my Chrono!!!

Is this a common thing or was there some weird alignment of the sun and planets I just didn't know about? Direct sunlight was off and on and it didn't seem to matter much how much light was on the thing. The readings were pretty much the same.

This post has been edited by theknightoflight: 24 March 2008 - 09:23 AM

[Gary1911A1]

Sometimes if I'm to close my chron will do the same. It sates to be 10 feet away from mine and if do that it's OK.

[pskys2]

I've also had reflections of the sun cause wierd readings. So if it's a cloudless sky watch where the sun is, it can sometimes cause false readings.

Chrony's always seem to work best on cloudy days. If you think that what might have been the problem try posting a couple of targets to cast the skyscreens in shadow.

[Shawn Knight]

Gary1911A1, on Mar 24 2008, 09:28 AM, said:

Sometimes if I'm to close my chron will do the same. It sates to be 10 feet away from mine and if do that it's OK.

I was about 15ft away. I was using the model with the remote screen and printer.

pskys2, on Mar 24 2008, 09:33 AM, said:

I've also had reflections of the sun cause wierd readings. So if it's a cloudless sky watch where the sun is, it can sometimes cause false readings.

Chrony's always seem to work best on cloudy days. If you think that what might have been the problem try posting a couple of targets to cast the skyscreens in shadow.

It was off and on with the clouds. Mostly we had very little sun. I will try the target idea though!

[kmitchl]

I had the same experience recently. We set up a Pro Chrono Digital and a Shooting Chrony Beta in series. The Shooting Chrony was always at least 10 FPS higher. Check the thread below for recommendations to reduce the inconsistencies.

I'm not aware of any quick method of checking the accuracy or calibrating a chronograph. Makes me wonder about the accuracy of the equipment used at matches.

http://www.brianenos...showtopic=35206

Keith

[Shawn Knight]

Thanks guys!!

[SA Friday]

That comes out to about 145ish pf on the 9mm load. That does seem a touch high. I don't know what gun you were using, but I get 130-133pf with 3.0gr of TG under a 147 Zero JHP (1.125 OAL and a WSP) out of my G34. I'm using 3.5gr of TG under a 135gr Zero FMJ and getting 130pf too. I don't have a lot of experience using a rifle primer with a minor 9mm load, but I think your chrono might be closer than you believe for the 9mm load.

[ipscbob]

I always keep some known PF ammo with me when I chrono and run some through as a reference first. I have owned two shooting chronys and a CED. The CED is much more consistent and tracks well with my results at major matches. The Chronys were a constant source of frustration and as a result are sitting on the shelf.

[HSMITH]

Make sure it is folded out FLAT, if it isn't it will read WAY high.

[LPatterson]

I put mine out of its misery by shooting it in the head.

[Shawn Knight]

ipscbob, on Mar 27 2008, 07:22 AM, said:

I always keep some known PF ammo with me when I chrono and run some through as a reference first. I have owned two shooting chronys and a CED. The CED is much more consistent and tracks well with my results at major matches. The Chronys were a constant source of frustration and as a result are sitting on the shelf.

Hmmmm... Makes me wonder....

HSMITH, on Mar 27 2008, 07:35 AM, said:

Make sure it is folded out FLAT, if it isn't it will read WAY high.

I looked at that and noticed it was a little bent. I didn't think anything of it because it really looked like it was very close to being correct. There did look like an adjustment that I will take a look at when I get back from DTC.

LPatterson, on Mar 27 2008, 09:31 AM, said:

I put mine out of its misery by shooting it in the head.

I hope I never do that....

[kgunz11]

Another good trick to getting better or more consistent readings is to take a sharpie and paint the projectile black. Always worked for me in less than desirable lighting conditions or when it was sunny one minute and cloudy the next. I can't explain why it works, it was just passed along to me and I tried it. It is also very effective for those last few minutes of daylight when the chrono doesn't want to read.

[ipscbob]

I've got 2 spare Chronys if you want them cheap. Seriously PM me if interested.

[Mark K]

I had my buddies Shooting Chrony out last weekend. I had a general idea of where the velocities were on my 40 and my 9mm, but when I shot, both were registering over 1200fps. I took a target, white side down toward the Chrono, and taped it over the screens, and everything settled into the appropriate velocity ranges.

Mark K

[AustinMike]

Overcast days are best for chronoing. I use the sky screens even with clouds, just to be sure. If the sun is out, I've found it's best to do it when it's high in the sky, but not directly over the chrony. If it's early morning or later in the day, try to position the chrony so that the sun is on the side, not either end, to help ensure light is getting to the sensors evenly. I use no-shoot targets in place of the screens sometimes if I'm getting weird readings and that usually helps. If not, make a circle with salt around the chrony and shake a chicken leg at it from each of the 4 corners.

[Shawn Knight]

It was slightly over cast but I am going to try shading the Chrony a bit more next time.

I might have to make some kind of box......

Hmmmm....

[ipscbob]

theknightoflight, on Mar 28 2008, 05:50 AM, said:

It was slightly over cast but I am going to try shading the Chrony a bit more next time.

I might have to make some kind of box......

Hmmmm....

Been there, done that with the shooting chronys. Save the time and effort and buy a CED and never have to worry about overcast vs. sunny days. They really are much better behaved.

[Dustdevil21]

kgunz11, on Mar 27 2008, 08:42 PM, said:

Another good trick to getting better or more consistent readings is to take a sharpie and paint the projectile black. Always worked for me in less than desirable lighting conditions or when it was sunny one minute and cloudy the next. I can't explain why it works, it was just passed along to me and I tried it. It is also very effective for those last few minutes of daylight when the chrono doesn't want to read.

Probably has to do with the contrast of the bullet. We paint the leading edges of our rotor blades when we do track and balance flights to smooth the rotor system out. The leading edge paint erodes off in time, and the camera that views the blades as they go by will sometimes get bad info if the leading edges are silver.

[Stuck in C]

Buy a 500 round brick of .22 or several from the same lot. Chrono it a few times, shoot it through friends chrono's, ask if you can shoot some through a match chrono, etc., until you have a good idea of the actual velocity. Save it (i.e. don't shoot it at gophers or your neighbor's cat) and use it as a velocity check when you are unsure of your chrono. It's what's known as a control sample. Of course use the same .22 pistol each time.

This post has been edited by Stuck in C: 10 April 2008 - 08:35 AM