Shooting Chrony accuracy and reloads ??

[Kyfarmer]

Just wondering what you fellows think about the accuracy of a Chrony. I've used one for a good many years but never had a lot of confidence in the accuracy of them.

Drug it out the other day and checked my Uberti Cattleman with 4.75" barrel shooting .38 Specials. The load was 2.9 gr. Red Dot with a 158 gr. RNFP cast bullet.
In 10 shots I had a high of 743 FPS and a low of 634 or an extreme spread of 110. Average velocity of 698.The average deviation was 34 and according to the calculator I found on the net the Standard Deviation is 39.11.

I then switched to my S&W K38 with 6" barrel and average of 10 shots was oddly a little less at 681 with an extreme spread of 58.

Just a little curious to see if this is somewhere near normal for my load. I have always seemed to get a bigger spread in velocity (according to the Chrony) whether I am shooting handguns or rifles. than most of the tests I see on the net.

I'm not much of a math man and don't really understand the Standard Deviation and all that. I have reloaded many thousands of both rifle and pistol rounds and don't really care about the numbers as long as they are accurate. I load all my handgun rounds on a Dillon 550 and feel like they are about as consistent as I can get them. What do you guys strive for in your reloads? Kyfarmer

[runfiverun]

i like my chrono and tend to believe it, i am usually within 100 of what the
book says, you can confirm your shot to shot by watching for vertical stringing
have noticed this and was able to confirm with chrono

also have noticed that the higher velocity ones have shot lower than lower vel.
in some of my rifles, which confirms the bbl vibration deal..

[Wicky]

I would put my trust in the Chrony. Differences between the two firearms are probably the reason for the differences. As a rule the further the difference between the screens the more acurate the data, my Pact runs 2ft between screens - a boolit casts a fleeting shadow and in theory the larger distance gives the chronograph time to 'see' the projectile.
I would think the difference between my chronograph and a Chrony would be negligable - have to find someone with one and do a comparison now!!
Your results seem fine - other people - different firearms, as long as you are close to other peoples readings I would accept the results from your unit.

[mike in co]

when was the last time you trimmed your brass?
is the brass all the same lot ?
is the neck tension all the same ?
neck tension/same crimp is an item you control, which controls the burn which (helps) control the velocity.
whats the diff in cylinders/throats between the 2 guns, whats the difference in cylinder gap ?

just a few things you control the will give you the spread you have......


and then you can ask questions about the chrony....


mike in co

[MT Gianni]

I trust my Chrony but use it most to look at changes in load development. I want to look at consistency and changes when swaping primers more than wondering if it is 50fps slower than my neighbors. Gianni

[jhalcott]

I mounted my Chrony in line with a Pact unit and both units read almost the same.Never EXACTLY the same but within a couple FPS. I use mine to verify hunting and accurate loads. After I have a good load, I see what the little things like changing seating depth do. It is easier to figure trajectories if you KNOW the velocity.

[35remington]

A few thoughts:

Make sure you're shooting square to the chronograph every time; that is, level and not shooting at an angle or where the bullet is five inches over the first screen and four inches over the second. You're trying to go parallel to the screens, and at as perfect a 90 degrees as you can to the sensor slots. Slight variances in how the bullet passes over the screens can account for some divergent velocity readings; so can different cans of powder and varying humidity when you're weighing your charge.

Try this trick; settle the powder in the rear of the case for each shot, then carefully and slowly lower to level and fire. This should significantly reduce your extreme spreads with the light charge of powder in the .38 special case, and may give you more confidence in your chronograph.

And yeah, different guns vary significantly, too.

[454PB]

Two things I have found that caused inaccurate readings on the Chrony:

Failure to fully open the unit. Even the slightest lack of fully open will throw off the readings.

Keep the unit as far as possible from the muzzle. My magnum rifles really produce a muzzle blast and it causes bad readings.

I've owned several brands of chronograph from Oehler to the Chrony, and I have full confidence in the Chrony.

[HeavyMetal]

If you have a good 22 pistol run some target rounds over your chrony everytime you set it up. These are very consistant and, if you use the same lot number each time, very repeatable. Keep a record each time you use the 22 and pretty quick you'll see a pattern and recognize good from bad set ups on the chrony.

I believe this was already mentioned but I'll say it again, these things are very sensative to muzzle blast! I actually glued some balsa wood to my "defractor" bars and pined card board 'triangles" to them to block the muzzle blast! Worked great!

As others have stated any chrono can be finicky, use the 22 as a guide and block muzzle blast and it will dial itself in!

[piwo]

I have the beta shooting chrony. I like it, trust it, and when I load up a load I have previously shot through it, the results don't vary. I trust mine........

[Kyfarmer]

Thanks for all the replies and thoughts about the Chrony. I'll try some of the suggestions in a few days. I'm particularly interested in the settling the powder to the back of the cartridge case with such low volume loads. I usually try and set it up about 10-12 feet from the muzzle of my handguns.

I neglected to say that I also shot a cylinder Wal-mart Remingtons out of my Ruger Single-Six at the same time. The average velocity was 920. 946,962,918,939,960,797. Not sure why the one was so low. I should have shot some more but it was windy and cold so I quit early.

[Lloyd Smale]

i had one that read about 250 fps fast but i sent it in and they calibrated it and it was pretty much spot on after that. I guess ill say its spot on when you can get it to read.

[Ed Barrett]

I have a chrony and bought an old one at an auction for $20, I tried it against mine and found it would read the same with the same loads. I tried mine against a chrony belonging to a friend of mine when he was at the range and found that his would read a 1fps slower when we had them in tandem (one behind the other so the same bullet went through both of them) The loads were between 900fps and 2200fps it was the same difference with either one in front, we switched to see if the bullet was slowing down between them. These test don't show accuracy but they did show repeatability and consistancy between chrony products.

[HamGunner]

I've owned two Chrony brand chronographs. Bought the first one for $59 in early 80's I think. I shot it dead when I forgot that I had taken the scope off of one of my rifles and had not re-zeroed. Just nicked the top of the display, but it was still DOA. Chrony gave me $25 off on exchange for a new one.

I feel that they are a great aid in working up loads. When my loads show steady powder increase with slowly decreasing gains in velocity, it is showing that I am just building pressure up. End of the line for increasing that load.

Any chronogragph that relies on light to trigger the measure will probably miss registering a shot or two if the light conditions are variable or too strong or too weak. I have used mine even in my basement to measure velocities of certain guns. Pellet rifle, etc. Clear skies sometimes will not contain enough light. A gray shade is usually needed to gather more light near the sensors. Cloudy days work better than clear.

I don't find that light conditions cause changes in readings, only failures to read. I am very happy with my Chrony. They are worth more than their price.

[Mk42gunner]

I have one of the Chrony's, I don't remember the model right now and too tired too go dig it out and look. That said, I always verify the battery is good and then check the reading with a 22 to make sure it is at least in the neighborhood of the expected velocity.

Robert