Chrony accuracy

[Trailblazer]

I have an Alpha Chrony about ten years old or so. I have been suspicious of its accuracy because my loads never chronograph at the speeds those books claim. Seems like most of my rifles are about 200 fps slow. My shooting partner has a newer Beta Master Chrony which he had never used. Last range trip I set them both up in line. The Beta Master has a remote readout so I set it in front of mine which you read off the front of the unit. I put a brand new battery in his but it only lasted a couple shots. I don't know if the battery was bad or if his Chrony is bad. It would work a couple shots at a time then I had to turn it off and let the battery recover and then it would read another couple rounds. In spite of that I got a few simultaneous readings.

The interesting thing is that the Chronys read closer to each other with larger bullets. My neighbors on the firing line were verifying their zeroes for hunting and had several rifles they wanted to clock. We fired a 264 Win Mag, 270, 7mm Rem Mag, 30-06 and 338 Win Mag over the two Chronys. The 264 is mine and I got two readings with both Chronys. The readings are 20 FPS and 21 FPS slower with the Beta. Unfortunately I didn't write down the readings from the other fellows rifles but the 7mm had less difference than the 264, the 30 caliber was better yet at about 5 FPS difference and the 338 was only 2 FPS slower on the Beta. This stands to reason because the Chronys sense the bullets shadow and bigger bullets cast bigger shadows.

If we get the Beta working I think I will try clocking some 22's up through 35 caliber to see if the trend holds up. Of course the other thing is that my Chrony is probably fairly accurate which means those dang reloading manuals lie!

[454PB]

One of the first things I learned when I got my first chronograph is that reported velocities in the loading manuals rarely match my results. I've owned a chronograph of one kind or another for 35 years. Another thing I learned is that you will pi** off a lot of people when you chronograph their ammo, and they will many times inform you that your chronograph is crap and inaccurate.

I presently have a Beta Master and a Competition Electronics. Your friends Beta Master has a problem. I can shoot many hundreds of shots across either one of my chronographs on the same 9 volt battery. I would guess a bad battery, and that's easy to fix.

After you've used one for a while, you will begin to see that varying velocities are the rule rather than the exception What you have to look and strive for is a small extreme spread. Differences of 20 to 80 fps. between shots are not unusual. On that rare occasion that you find a load that has an extreme spread of 15 to 30 fps. and is accurate, stick with it. Ambient and barrel/chamber temperature have an effect, and it can go either way, up or down. I own two Ruger .338 magnums, and the same load will vary 50 to 100 average fps. between them.

The one time I had a problem with my Chrony was when I failed to open it completely. Change the distance between the sky screens by the smallest amount and it throws the readings off greatly. I use the glint screens everytime...even if it's cloudy. I don't have a problem with boolit size, I'm careful about centering them directly over the sky screens and about 4" above them. I DO occasionally have trouble with muzzle blast in some of my bigger blasters, and place the chronograph as far from the muzzle as possible.

[shooting on a shoestring]

Amen to what 454PB said. Chronographs are great busters of advertised and published velocities.

I use an Oelher 35P that has a proof channel. Its a 3 screen setup that measures from 1st to 2nd and from 1st to 3rd, compares the two velocities and flags the data if there's a significant difference. That's pretty much what you did with two Chronys.

I don't believe the absolute velocity is as important as the variance in velocity. Whether my chronograph is exactly calibrated, or off by 100 fps really doesn't matter. What does matter is that it is repeatable, precise.

I track changes in powder charge weight vs. changes in velocity. When I have several data points and see the change in powder weight gives smaller and smaller changes in velocity, I know I'm close to max.

Its also been a real eye-opener to see how powder position (especially in revolver cartridges) makes a huge difference in velocity. Its more dramatic for some powders than others. Its helped me choose what loads to carry for defense.

[Bret4207]

I also use the top screens, even if it's not cloudy. Fresh batteries, make sure the connections are clean and everything is stable on a good tripod or table- nice and steady. I also find my velocities below book by a good margin. I started out with a friends Oelher and that was an eye opener. My vaunted 22-250 wasn't really breaking 4000 fps, more like 3750. And those super 9mm's we were paying big money for with their +P+ rating were pretty close to book stated standard velocity, 1100+ vs 1300. OTH, the 30-30's were about right as were the 45 ACP, 22 lr etc.

I don't believe in advertised velocities anymore. I just hope for the best and see what I get.

[BCB]

I have an old, old, Chrony (maybe one of the first made?) and it always seemed to be pretty darn accurate. Nope, it never showed me “book velocities”, but many of the velocities it showed me, I was able to “mostly” verify by shooting at know distances and seeing P.O.I. of the particular bullet with the Chrony recorded velocity.

One quark that mine has is the reading on the 1st shoot when it is being used. It seems to mostly be radical—although not always. SO, I fire a shot over the Chrony to “set” it the 1st time and then I start recording what I am interested in after that reading. For the $$$$, mine has been very good I think. Good-luck…BCB

[Freightman]

Published data is mostly inflated to sell the product! I work at an archery/gun store part time,(hey have to support this habit) anyhow the published speeds for bows is a term OEM which is not a realistic number just a selling point. The OEM number is a arrow with no point,fletchings and is the lightest shaft they can make, basically they are dry firing the bow (not a good idea). I supect that the published data of ammo is the same, that is a selling point.
I do not let just anyone use my Crono for the reason that was stated, they don't believe it anyhow so to keep the it is junk down I do not offer it.
"Faster bullets (cars) older whisky, younger women" actually it is bragging rights that is important.

[hivoltfl]

I like others here take published velocities with a grain of salt, I am also sceptical of my chronys accuracy on speed, what I look for when using it is how consistant the velocity is, If I can make tham all go the same speed I am pretty sure I can make them hit pretty close to the same place.

My 2 pennies worth.

Rick

[redbear705]

I have a Master Beta and I must be lucky because when my ammo was teasted at the 2007 Michigan IDPA Championship the tested ammo was the same velocity(very close) as what my chrono said it was.

I shoot a revolver with a 2 3/4" barrel.....I asked that they use my gun to test the ammo and they agreed.

The velocities were 1060,1051 and 1067.....using a 150gr lead r/n(LEE) and 4.1gr titegroup.

My numbers were slightly higher at the range but it was alot hotter that day then at the match....but I still met the power floor with no problem. :) even with my short barrel!

[Bullshop]

Chrony accuracy should be perty easy to acheve. About 4 moa aught a do it. There have been other threads dealing with this, check arcives.
BIC/BS

[Sundogg1911]

If you ask me, book velocitys are a lot like Car companys milage reports. I've never in my life gotten the milage the companys say I should. I think it's one of those "In a perfect world" deals. I had a Chrony Beta, and a Pro Chrono at the same time, and the readings were very very close on both, but usually under what the ammo boxes said it would be. I use my Chrony to reach major power factor for IPSC, and when it's tested at a match i'm usually right on the money. I no longer have the pro chrono (Thanks to a Buddy putting a .223 through it) but i've been very happy with my Chrony.

[Trailblazer]

Everything posted is right on as far as I am concerned and I use mine the same way. I told the pair that wanted to chrono their hunting loads that they were doomed to disappointment and they were. All of their loads were 100 to 200 FPS under what they expected.

I set mine at 15 feet because I don't get reliable readings with the magnums if it is any closer. I have nearly killed mine a couple times. I have a gas check strike just left of the on-off switch and a bullet nick in the top edge of the housing.

My original point was that the two Chronys were in closer agreement with larger bullets which means that the variation in velocity with smaller bullets may be due to the unit not being able to sense them as accurately. If so reliance on extreme spread or standard deviation with small bullets isn't useful.

[Single Shot]

I use an F1 MASTER.

Book data is not always Chronographed. A lot of it is calculated. In fact the Lyman manual I have lists a "most accurate load" for each cartridge based on calculations if you check the foot notes.

Same as the EPA mileage stuff mentioned above.

Main goal is to get your standard deviation as small as you can for a specific load and weapon. :drinks:

[Moose]

Got into Chrony work a good many years ago - say 20? And the reason for it was doubt concerning published black powder velocities. Having been a shooter for about 60+years I do have a little experience between the bang and the can jumping up. All you old 11B's read "Burst on Target"- In any case, that started an on going process that is still playing. Now, if you understand how a particular chronograph works, you will not have so many doubts about accuracy of result, especially where repeatable results are concerned. There is one area that most people ignore- and that is how far from the muzzle is the first screen. At one time at Aberdeen Proving Ground the first Small-Arms array was 33 feet from the muzzle. Then there was a metric set up we used at the Fort Ord MKTU to check centerfire reloads. In either case it would make a difference in something like "E-Z-X's" match grade 22lr, which had a nominal mv of 1084 fps. Nominal means published. On the 33 foot setup, you might get 1035fps, +/- 8fps; SD was quit low, and the stuff would group well within a MOA. On the Metric setup (5 or 7 m., I think) it might read 1060 fps +/-7 fps. The point is, the chrony either works or it doesn't. Oh, you can get phony values all right - weird cable faults, blips in the power supply etc.. but by and large, the chrony tells the truth. Just for the ducks of it, check it with a standard bb gun (the red-ryder type). You will be interested in just how consistent the old clunk is. Then try a few rounds of match-grade 22 LR. Amazing. The thing is, you are interested in the SDeviation and ESpread, if you are going for accuracy. Keep those values low and you can get tight groups, all things being equal. Velocity is not all important. Like everyone has said, it's like the EPA blurbs. Blurbs. And if you are having trouble with only getting a few value readings before the battery goes flat, get some fresh ones, shut it off when done, and don't hesitate to contact the Chrony people.. And true enough, don't chronograph other people's pet loads - Unless they are very good buddies, they are not going to believe you. Big macho emotional thing, I guess..

[felix]

A chrono works/tells only for that ammo-gun in combination. Put the round in a different gun, including a commercial pressure gun device, the pressure-velocity results won't be reliable at all. Tighter fitting guns will show more peak pressure for sure, and perhaps deliver more muzzle velocity as well, but not necessairly. Ammo-gun dynamics plays a significant role in total boolit behavior, inside and outside of the gun. ... felix