A year or so ago I purchased a Chrony. To my suprise, after firing several different rifles through it, I was disapointed with the velosities that I was getting.

The best I can get out of:

Rem M700 222 50gr. bullet 2800fps.
Rem M700 22-250 50gr. bullet 3100 fps.
Win M70 338 Win.Mag. 225 gr. bullet 2750 fps.
Win M70 7mm STW 150 gr. bullet 3100 fps.
Win M70 270win. 140 gr. bullet 2800 fps.

These are the highest velosities that I have gotten and they are all at Max. or above Max. listed loads.

I have heard this before about a chrono being a reality check between what is listed and what is real, but in 5 different rifles I can not reach maximum published velosities.
It is no big deal in my .222 but why am I burning up 82gr. of H1000 in my 7mmSTW to get .280 Rem velosities?
Not only from the numerous loading manuals but from the claimed velosities that are on this board. I do not believe there are that many bullshitters out there.
I don't know jack shit about chronographs. How accurate are these Chrony's?
I will try to find someone else with a chrony to cross referance. I don't know if I will be able to handle the reality check.

Daryl

If possible, shoot against another chrony. Your numbers sound a little low. Especially your 270.

You could maybe "proof" your chrony using match grade .22 ammo. That is supposed to be pretty close to what is on the box.

My feeling about some of the manuals is that the velocities they show are high - at least in most of my weapons the upper velocities they show are reached with more powder than they used in the manuals - the gear they use to develop these loads with are generally not factory rifles but are specially made actions(tight chambers) and fresh new barrels that may not accurately reflect real world conditions (factory rifle). Product liability has forced conservative loading data. The beauty of your chronograph is to develop loads that perform to your expectations using the other data from cases(head expansion or loose primer pockets or short case life) and primers (flattened appearance)to judge safety of your rounds. However, I do have a 270 that will not take most of the maximum loads listed in some manuals but will develop the upper end velocity with lighter loads but it is the exception - but it is one of those reasons to proceed cautiously until you know your rifles characteristics.

Yukoner, welcome to reality. I remember some years back I thought the same thing when I got my chronograph. To make a long story short, that was my main motivator for experimenting, as most of my reloading up to that point was done for economy and accuracy.

What I have learned:
-most data was optimistic
-Lyman, VihtaVuori and Ken Waters were among the best
-the slowest powders aren't always that slow(they chang positions when used in different calibres, as well as same calibre different case shape)
-never buy a case of powder unless it is 4895(universal), until you have experimented first
-my best loads started on a hunch
-7828 works the best in the mid-sized Weatherbys
-didn't like H870, H1000,[too dirty and too fast (respectively)]
-VihtaVuori Oy powders did the best job for my slow shooters

Good luck packrat

Post the loads and barrel lengths and maybe that will give us a clue as to whether the Chrony is miscalibrated or the velocities are just on the slow side.

By the way, these aren't from dead-of-Yukon winter tests when the temperature was 60-below, were they?

There are slow & fast barrels on rifles & pistols. Some of your vel. sound about right, your .270 & 7STW sound slow. As others have said, barrel length, & your loads may cause the variation. When my choro. vel. look funny I check w/ a known load w/ litle variation. A .22match or .45acp match factory load will be very, very close.
I once had a 2 3/4" Ruger .357 that was faster w/ every load than my 4"S&W. Welcome to the real world.

There is an article in the July Varmint Hunter that directly addresses your question.

If you are shooting during the middle 2/3 of the day, in full sunlight, or under 'hazy bright' conditions, where you can still see the shadow of your Chrony and tripod, your displayed numbers are extremely accurate.

Published velocity data is taken in special test barrels, that are cut to minimum SAAMI dimensions. That means that they will routinely produce higher pressures and velocities than average guns will. For a rifle, the difference is usually about 65 fps.

Thanks for the replies.

I have used my Chronograph on cold winter days but the velosities I have listed have been on warm days.
I don't have my load data with me, but off the top of my head:

338 Win.Mag M70 26" barrel
72 grs. IMR 4831`
225gr. partition
Fed 215
Vel. 2740-2750 fps.

270 Win. M7O 22" barrel
55 grs. IMR 4831
140 Sierra Game king
Fed 210
Vel. 2800-2840 fps.

7MM STW. M70 26" barrel
82 Grs. H1000
150 gr. Sierra Game King
!50 gr. Partitions
Fed. 215
Velosity. 3090-3150 fps.

For my Rem. M700's in the 222 and the 22-250 I know that I am at least 4 grs. over max. published loads.

I have tried a couple different powders and the loads I listed are about best I could get.

I won't waist any more of your time on this. I do know of someone with a couple of Chronographs and I will do a cross check.

Thanks again,

Daryl

I think it's likely your Chrony may be off some .

However, I have been dissapointed by the velocities gotten out of many loads tried with single based powders since I aquired my chrono .

I'm not saying it's a hard and fast rule , but I have the general impression that loads tried with the double based powders like the Alliant series seem to come out closer to your expectations .

The most common source of chronograph "error" is an error in spacing of the screens. The Chrony is supposed to be "pre-spaced", but take a measuring tape to it to make sure. Also, if the two sensors are not perfectly vertical, this will change the effective screen spacing. If they tilt away from each other so that they are effectively, let's say, one inch further apart than the standard (I think) of two feet, then an actual velocity of 3000 fps would give a reading of only 2880 fps.

That's one reason that I like to use a wider screen spacing, like the four feet that I have my Oehler set up on. Not only can the chronograph be more accurate with the wider spacing, when you have a 1/32nd inch error in screen spacing on a four foot span, that is half the error of a two-foot span or only 1/4 the error of the same mismeasurment on a one foot span.

Wally: My point with the Chrony (and I've never worked with one) is that while the screens (sensors) should be properly spaced, as I understand the Chrony, it unfolds to expose the sensors. If it unfolds "too far", that is it is slightly bowed upward in the middle, then the screens would be tilted away from each other, effectively increasing the distance between them. I am only speculating here, but this problem would seem possible and would result in lower-than-actual velocity readings due to greater-than-calibrated screen spacing.

On the other hand, not all of the velocities that Yukoner listed are out of the range of expectations, so there may be no problem with his Chrony. My advise would be to spend a few bucks more and get an Oehler, then you would have no question.

Okay, guys...

Chrony's are NEVER "too slow" as it would require a cape buffalo to stop on one to bend it out too far.

BUT, they can be too fast, if not opened all the way.

I've done field experiements with 3 different chronys and my pact pro... guess what? the "error" was less than the SD. Had the elcheapo red box (delta), a gamma master and a beta master, and a pact pro. They all read within the SD of the "proof" being the pact. If the pact had a 30fps SD, all read within that range....

.01% .. that .0001 error, or .3 FPS of a 3000 FPS load, is was ALL of them are guarentied at.

Getting tired of folks trashing tools they haven't or don't use.

The simple fact is his rifles are not acheiving the same ballistics as the books are... and the books generally use LONGER barrels than a hunter would use.

This aint a "slam teh chronomaker" rather a "what should I do question.

I aggree with the poster that said use a match 22 to check to see how far off. If it's 2% off, send it to chrony and ask for it to be evaulated.

The only people that complain about "cheap shooting chrony piece of junk" as those that haven't used them.

jeffe

FWIW, I ran your 270Win load through QuickLoad and it predicted a MV of 2831fps. I'd bet your Chrony is right.

Yukoner;
Just two weeks ago I was at the range and a friend had brought his "Pact" with him. I had my cheapy Chrony F1 so we decided to make some comparisons. (Something I've been wanting to do for a long time)
Anyway we found out that my "Chrony" was indicating 30 to 40 fps slower than his "Pact" with same exact loads. As stated above sd was running close to this as well and overlapping each other. In the 3250fps for one load, to 3350 fps range for the second.
So I am confident my "Cheapy" is running plenty close enough for my needs.

Also your load for the 270:
270 Win. M7O 22" barrel
55 grs. IMR 4831
140 Sierra Game king
Fed 210
Vel. 2800-2840 fps.
Is right on the money, + or - a few FPS!

[ 07-16-2003, 21:52: Message edited by: Marsh Mule ]

For comparisons as to what the manuals state and what I actually obtained in velocity differences, go to Table #1 on my pages.

Most manuals will list "optimistic" (to be kind to them) velocities.

As for the accuracy of the Chrony systems? I have three of them and have never had more than a 0.5% difference between them.

I'll bet on the Chrony too.

There may be something wrong with your Chrony. If only one or two rifles were failing to give expected velocities, I'd say, OK, that can happen. As a matter of fact, it sounds to me like at least your .338 and .270 loads are doing just about what those powder charges you mentioned are expected to produce. What does your Chrony say about some of the different .22 rimfire loads' velocities? These should be right on with factory specs, or your Chrony's out to lunch.

I am now using a Chrony also, and it is right in line with the figures I used to get with my old Oehler. Most of my ammo has performed about like the books said it would, none much better than that, but usually not too far off, velocity-wise!

[ 07-16-2003, 22:16: Message edited by: eldeguello ]

One subtlety with the Chrony, that you should be aware of: If you use the extension rods, to raise the diffuser screens farther above the photocells, it will decrease your readings by about 25-30 fps. So just don't use the extension rods.

As to the "unfolding" issue, as stated above, the error is very small. For example, if you're shooting not quite square with the Chrony, the reading will decrease with the cosine of the angle. You have to get a fair bit of angle before the cosine drops below .99. Hence, as stated, the error is much smaller than the standard deviation of the results.

yukoner:

I have found that my chrony gives accurate readings. Some are slower than published velocities and some are higher. However, with handloads I come normally pretty close to the info in the manuals most times.

I don't use the screens, got just easier to use the chrony in the shade and I quit getting error readings. I put in on a bipod, and use the hood of the 4 Runner to shoot off of. Usually when I am chronographing 10 rounds, It is easier to just go out in the woods about 3 miles from home than to drive thru town, 15 miles over to the range, sign in etc.

It is one of the best $69.00 I invested in shooting. Several friends have the Pacts etc, and after they saw how quick I set up the chrony, and break it down, they have also bought one and use it a lot. When they don't want to go thru the hassle of setup and breakdown of the Pact. Testing has found no deviation on the Chrony to be concerned about.

The Chrony subject comes up regularly on 24hourcampfire -- one trick several there have recommended is to put a piece of Scotch tape over the sensors, that way you can scrap the diffusers (mine broke a long time ago anyway).

This seems to reduce variations due to the angle of the sun. However, take the tape off when shooting in a drizzle -- puddles of water on the tape will act as lenses and you will get all kinds of screwy readings.

John

This is the wonderful thing about having a chronograph, all the bull and wild guesses don't change the number that comes up on the screen. It wouldn't hurt to check it against another, but I'll bet it's fine. As an example, I doubt the .270 load is any hotter than that as I used to load 60 gr. H4831 with a 140 Hornady and shot a little over 3000fps out of a 26" Ruger No.1. there is a hell of a variation from one gun to another,as you'll find out you max loads are nowhere near max. My little brother almost cried when his 55gr. 243 load that the manual said was 3900 fps actually went 3588, the load worked good till he found out how slow it was. I've used a chronograph since the 1970's and it's an eye opener and one of the most effective tools for a serious loader.

The only velocity that jumps at me is the 22-250 velocity. That's really anemic--what's the load?

My favorite load for my 338 is 72.0 gr of H4831 shooting a 250 Swift. Looking at a few books, I figured velocity was in the area of 2750 fps. It has been instant death on numerous head of big game including some heavy african stuff.

When I shot some rounds over my Oehler, I found out the velocity was only 2525 fps. I was stunned and full of self-doubt. How can I ever kill another animal with such an anemic load?

On the other hand I've got a custom 270 with a minimum spec chamber. A 130 grain Partition over 55 grains of IMR 4350 (Nosler manual max) gives me 3225 fps and I'm getting right at 3100 fps with some, what I thought were reasonable, 150 grain loads. A friend shot his 7mm STW over my chronograph and found out he was getting similar velocities. He likened it to finding out your girlfriend used to be a guy.

Youkoner,
To quote a former great president,"I feel Yo'pain."
When I checked the velocity of my 30/40 Krag load,that was taken from the book,I was not sure that the new Ohler#35 was working right.
The book said that I was getting 2650 FPS,but the chrono read "avg 2490 FPS".
I never dreampt that the book could be that far off,but it was.
That was a max load;I added .5 more powder,to get an even 2500 FPS(over max)
Frank

I have two chronies and both agree very closely with each other.If you don't use the diffusers results can be unpredictable.I have seen very fast and very slow 7mmstw's but yours is by far the slowest.I get 3480fps and 3530 fps with 140gr bullets and 80gr of imr7828 out of my two 7mmstw's but I know of one sendero that only produces 3370fps with 140gr bullets and shows pressure signs if the powder charge is increased.One thing that I have noticed that might interest you though is that the last lot of h-1000 extreme that I bought is very mild and decreased my velocities in my 7mm imperial mag by almost 100fps from the old lot of h-1000(not extreme)I had to increase the charge by two grains to regain the lost velocity.It may be that you have some of this milder powder and need to increase the powder charge to compensate.

[ 07-17-2003, 07:47: Message edited by: stubblejumper ]

When I first got my chrony, I tried it on my 257 JDJ and found I was getting 4500 fps with a 100 grain bullet (Who says JD doesn't make a hot cartridge ). I returned it to the factory, and when I received it back, the speed had dropped to around 2500 (Maybe thats why I eventually shot it with my muzzleloader). If you question its accuracy, I would compare it to another chronograph.

[ 07-17-2003, 07:47: Message edited by: OldFart ]

Thanks for the support. I am starting to accept the reality.

My biggest disapointment was with my 7mmSTW. I had a M70 7mmRem.Mag that would get 3050fps with a 160gr. Sierra behind 73grs. H1000. Stubble may be on to something. The H1000 for the 7RM was 8 years ago. The H1000 for the STW was recent.

It is funny how a guy gets when he finds out his favorite guns aren't performing like he thought they were. Like getting dumped from a nice girl(from what they tell me )

I can live with the .338 and the 270. I won't change a thing for them. They shoot as good as my 222.
I am going to work on my STW after I check my Chrony with some 22lr. Match ammo.

Kraky,
give me a day or two and I will post the load.

Daryl

I had a 7STW with a 24" bbl and was very, very disappointed with the velocities I was getting. Several of my friends also had some and the ones with 24" bbls were getting similar velocities. One friend had a 26" barrel and when I shot my loads in his the velocities were much higher than you would expect with only a 2" increase in bbl length. I've talked to more than a few other shooters with 7STWs and the story is pretty much the same...if you don't have at least a 26" bbl you are wasting your time.

Yukoner,

Isn't the truth a real pain? Still, velocities seem low. I'll comment on each by caliber.

.222 Rem. You didn't indicate what your load is, only that it is 4 grains over book. My experience with the .222 seems that it is difficult to get 4 grains over book of powder into the case. And if you did, pressures would be sky high. I have gotten excellent results with H-4198, H-Benchmark and BLC-L2. I'd recommend you give either the 4198 or Benchmark a try. The factories claim 3100 fps, but a little over 3000 fps is more realistic if your not using a 26" barrel.

.22-250. Once more, 4 grains over book is a little hard to take. 3100 fps with a 50 grain bullet is far off the results I have had with several different .22-250s The M-700 VLS I'm using now really likes H-Varget and H-4895. 3600 fps with a 55 grain Nosler Ballistic Tip bullet is no problem at all. 36.5 grains of Varget reaches 3750 fps and 35.5 grains of H-4895 reaches 3690 fps with the same bullet. Depending on the powder you're using, if you're not getting something close to this, then you are using the wrong powder or perhaps an over-sized bore or chamber.

.338 WM. I don't think your too far off on this one. I've had better results in the .338WM using H-4350 powder. Due to the bore size, I don't think either of the 4831s is efficient in this cartridge, even when using a 250 grain bullet.

7mm STW. Sorry, the only thing I can do is speculate, never having had a 7mm STW. I've played with H-1000 though and it may be a little slow with the 150 grain bullets. I think it might be better suited to the 160 grain or heavier bullets. I used H-1000 in a 7mm RM with the 160 grain and it gave me higher velocities than other powders. I found that the Fed. #215 primer gave better ignition and more uniform velocities and accuracy than the CCI #250s I usually use in large cases full of slow powders.

.270 W. While Mr. O'Connor touted the use of H-4831 in the .270, I've found that H-4350 has given me better, more uniform results with all bullet weights, from a 22" barrel. I played with the 140 grain Sierra Gameking. Velocities usually ranged between 2960 and 2980 fps. That's enough to make me happy when using a 22" barrel

I load for accuracy in all my rifles. I think bullet placement is more important than 100 fps velocity more or less. So far it has always worked for me. Let us know what you end up with. Good luck.

[ 07-17-2003, 12:26: Message edited by: BigBob ]

Since low velocity is standard, the first thought is to blame the chrony, the second to call data publishers liars. Check your scale first. You think you're loading max loads but may not be actually doing so. That's where I would start.

Yukoner: I declare your 222 and 22-250 loads are WAY below what they should be! I will not comment on any of your other results at this point.
I have an Oehler chronograph and taking into consideration differing barrel lengths my results with a myriad of calibers and many duplicate calibers in more than one Rifle over the past two decades - I have been happy with my feet per second results with the manuals published data! I will admit the manuals are usually a tad more optimistic! I am a notorious non hot rodder and stay away from maximum loads religiously! But not far away! I have never have settled on a load that was above maximum in any Rifle I have ever owned. I don't go there! I don't want to! Barrel life, brass life, the safety of my eyes is 1,000,000 times more important than wringing the last foot per second out of my customized handloads!
I think something is wrong with the Chrony set up either you have enetered the wrong distance between the screens or the chrony is burped! Also how far in front of the muzzle is the midpoint of the timing screens. I have a formula downstairs that gives the amount of FPS to add to your readings to obtain true muzzle velocity once this midpoint between the screens and that distance from the muzzle is determined! But even that formual and adding typical results on would not give proper velocities for the 222 and 50 grain bullets or the 22-250 and 50 grain bullets.
How about this! On a calm day go to the range with your 22-250 and sight it in dead on at 100 yards! Then on that same calm day from an absolute steady sand bagged in rest, shoot the 22-250 at 200 yards! Measurely as precisely as possible the center of the 200 yard grouping and its exact distance below your point of aim! Once you have obtained this "drop" distance at 200 yards go to a ballistics program or your bullets reloading manuals drop tables and see what that bullet should be dropping at that range at your elevation! This is kind of working backwards but I am sure it will work for you as I used to use this method before I got my Oehler 20+ years ago! I hope you understand my crude explanation to try and verify or disprove your Chrony's accuracy!
Good luck.
Hold into the wind
VarmintGuy

jeffeosso,
I agree 100%. If you take a 10 shot group like the chrony says to do, and you get a SD of 30 or less, I will gaurantee that it's not the chrony's fault. All I can say is welcome to the real world. Most all of the manuals use 26 inch barrels and are in controlled conditions. They're our to sell their product so the higher velocities with the longer barrels. Basic rule of thumb, from Sierra, + or - 25 fps per inch of barrel length. Take your barrel length and that in the book, do the math, and then chrony, you'll find that the chrony is more right than wrong.

[ 07-18-2003, 07:56: Message edited by: Robert M Boren Sr ]

Yukoner, now you know how us 7mm Rem Mag owners felt when we found what our velocity really was.
I have read that you should never Chrony a magnum rifle. Wonder why?

Here's the only way to fix that Crony!
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I had no problem getting 3200fps out of my 7mmremmags shooting 140gr bullets.My 7mmstw's deliver 3500fps with 140gr bullets and my 300ultramags produce just under 3400fps with 180gr bullets.These velocities meet or exceed the published velocities for these cartridges.All are carefully worked up handloads that are perfectly safe in my rifles.The 7mmstw's and ultramags use 26" premium barrels and the 7mmremmag wore a 24" factory barrel.Factory loads in factory rifles usually fall below published values but in most cases handloads in factory rifles meet them and handloads in quality aftermarket barrels often exceed published velocities.

[ 07-19-2003, 00:56: Message edited by: stubblejumper ]

It all depends on the rifle and it's bbl. My Ruger M77 in 7mm Rem has to be loaded with 73 gr of H1000 to get 2950 w/a 154 gr.I don't get any pressure signs with it or the 160 Part. so I could probably go higher. This load is over max but good only in my rifle.I have a pro-chrono and standard loads only get 2750.
My 6mm Rem gets what the book says it should so each rifle is a problem unto itself.

Ooops, Bullshit alert! I got my load data with me. The B.S. was not intentional(and I did not inhale )

Reloaderman,


These are the actual loads from written notes.
Rem 700
23 grs. 3031
cci Mag Small Rifle
50gr. Nosler B.T
Vel.avg. 2,850fps.

Rem700 VSF 22-250
38.5 grs. H380
55 gr. Nosler B.T
Fed 210
Vel. avg. 3,520 fps.

Rem 700 VSF 22-250
37 grs. Varget
50 gr 52 gr. Speer H.P.
Fed 210
Vel. 3,630fps.

Win M70. 338WinMag. 26"barrel
Off hand practice load.
70grs. IMR4831
200gr. speer
Fed 215
Vel. 2548 fps.

Same day, same gun(338)
74 grs. IMR4831
225gr Nosler Partition
Fed 215
Vel. 2,890 fps.
Above max. listed and I recall the case capacity was all used up. This load was accurate in my rifle.

Win. M70 7mmSTW.
82 grs. H1000
Fed.215
150gr. Nosler B.T.
Vel. 3,080 - 3,150fps.

The 270 load is same as above.

I am going to try some other powders in the STW.

Daryl