Chronograph ??

[Woodcutter]

Here is a little video comparing the Oehler and the Chrony.

http://youtu.be/EzNKUAgpKNY

Thanks for posting that video Dennis. I had watched that video before. It is a very well done video. However, I disagree with his conclusion that the Chrony is adequate for testing loads. He seemed to be only concerned with average velocity for computing drop tables. In that respect, in his test, the averages computed by both chronographs were very close, and I agree that either one will work for this purpose. However, for developing the most accurate and consistent load, one must also be concerned with the consistency of the velocity of the load. The best measure of this is the Standard Deviation (SD). In this test, the Chrony's computed SD is more that twice that of the Oehler. Please note also that he made an error when he posted the extreme spreads (ES). The ES for the Oehler was actually 80 and for the Chrony was actually 138. When trying to get a low SD for long range shooting, I want the most accurate number I can get, and my own tests of the Chrony support his findings, that the SD values given by a Chrony are sometimes of by a factor of 2 or 3. This may be fine for most shooters, and is fine for computing power factors for IDPA, but is unacceptable to me. I am not shooting in IDPA matches and I do not care what the power factor is for my loads. I want to be able to consistently hit what I am shooting at, even at long ranges.

So I guess my conclusion is, which chronograph is adequate depends upon your intended use. For my purposes, a Chrony is a lot better than nothing, but it does not completely meet my needs. That is why I have been on a quest to find the most consistent one that is within my budget. I thought the Oehler was the only one, but now I have found out that if I get two ProChronos, that may be just as good or better. The thing I like about the ProChrono is that you can buy a computer interface for it (although it sounds like the software is in need of improvement).

 

[Woodcutter]

Glocktogo,
You said you have the ProChono Digital. What accessories do you have for it? Do you have the computer interface? If so, how do you like it?

 

[lkothe]

Got a Caldwell from Jerry's for fathers day.
Time to play!

 

[Glocktogo]

Glocktogo,
You said you have the ProChono Digital. What accessories do you have for it? Do you have the computer interface? If so, how do you like it?

Just the unit. All I really do any more is test competition pistol loads for power factor.

 

[Maverick1911]

I am going to ask a genuine question that I am sure I willed get mauled for asking.....why do I need to know the speeds of my rounds? I reload and for .223 I use H335 22.5 grains with a 69 grain sierra hpbt....my 3 shot group at 100 was good so that's what I use....would I be better basing loads off of speed first? I ask because I am trying to get my dopes out to 600 yards and am slightly frustrated....not sure if my bullets are sporadic because I'm still new to the long range scoped rifle game or if my bullet is not the best for my particular rifle? One can go nuts trying to figure out what the issue might be!

 

[dennishoddy]

I have had the wind blowing or gusting so hard the tripod and crony were lifted off the ground.
Careful using it on a 55 gallon bucket.. wind could make a mess of it.

LOL, I've wasted a couple of the rods that hold up the sky screens.

 

[dennishoddy]

I am going to ask a genuine question that I am sure I willed get mauled for asking.....why do I need to know the speeds of my rounds? I reload and for .223 I use H335 22.5 grains with a 69 grain sierra hpbt....my 3 shot group at 100 was good so that's what I use....would I be better basing loads off of speed first? I ask because I am trying to get my dopes out to 600 yards and am slightly frustrated....not sure if my bullets are sporadic because I'm still new to the long range scoped rifle game or if my bullet is not the best for my particular rifle? One can go nuts trying to figure out what the issue might be!

The ballistics coefficient determines how the bullet will fly down range. A chronograph will determine the bullets speed, and you can develop your dope from that data.

Factory's publish guidelines but there are lots of variables in long range shooting beyond what they say.

Barrel length, humidity, barometric pressure, etc all have an effect. At short ranges like 100-300 yards, there is not much effect by the atmospheric variables.

Out to 600 to a grand, the game changes.

 

[Driller]

I am going to ask a genuine question that I am sure I willed get mauled for asking.....why do I need to know the speeds of my rounds? I reload and for .223 I use H335 22.5 grains with a 69 grain sierra hpbt....my 3 shot group at 100 was good so that's what I use....would I be better basing loads off of speed first? I ask because I am trying to get my dopes out to 600 yards and am slightly frustrated....not sure if my bullets are sporadic because I'm still new to the long range scoped rifle game or if my bullet is not the best for my particular rifle? One can go nuts trying to figure out what the issue might be!

When developing loads, particularly for long range shooting, muzzle velocity is good information. During load development, knowing the speeds of the bullets (and therefore the average speed, standard deviation and extreme spread) will tell you how consistent your loads are. Additionally, an accurate muzzle velocity is necessary for accurate ballistic calculations. A 50 fps error in bullet speed will result in a point of impact error at 1000 yards of a couple of MOA depending on the atmospherics. If the velocities of your reloads vary within a range of a 100 or so fps, it's going to be hard to get any consistency at range.

 

[ASP785]

When I use my chronograph I am looking for consistency among a group of reloads. ES and SD are very important in shooting for accuracy. Even at 100 yards, vertical stringing from varying velocities can show up and it just gets worse the father you go. Even though there is good ballistic software available I still just use velocity metrics to get me close to the target. You still have to shoot at each range to develop a good range card.

 

[Glocktogo]

The extreme spread and standard deviation will really come into play at 600 yards. At 100 yards you might have a very accurate load in your .223, but still have significant spreads. At 600, that same load will not print nearly the tight groups that a load with low spreads will. All else being equal, matching the load to what your particular barrel prefers is the best method. However, that doesn't mean it's an accurate load, just a load your barrel prefers. An accurate load will be accurate in most barrels because the consistency is there. Without a chronograph, you can't know the variables you're working with.

As a competition pistol shooter, I'm looking for two things. Power factor and low standard deviation. I have to make the minimum power factor in order to legally compete. I don't want to go too far over minimum, or I'll be fighting unnecessary recoil. The low deviations ensure the gun cycles consistently and muzzle rise is repeatable, which aids in accuracy and control.