I am on my second Chrony Alpha Master. I returned the first one to Midway as it was spitting out gibberish numbers. I tested some 38 special and 357 Mag loads the other day.
I loaded some more and will try again this week.

I know there are a lot of variables between real life velocity readings and published load data but how much to allow for change in barrel length? I seem to remember reading somewhere it was almost 100 FPS (depending on caliber, powder, primer yada yada)

I test fired some 22lr and they were in the 1000 fps range

For example: I tested 2 strings of 10, 38 special. 158gr MBC 158 gr LSWC with 3.7 grs HP 38 out of a SW M 67 4" barrel. The gun is dead nuts accurate.

I am only listing the 38 loads as the 357 where similar, higher velocity but not what the book states using 2400 powder.

1st string AVG FPS 510, ES 25, SD 6.78
2nd string AVG FPS 514, ES 18, SD 6.16

So I can not complain about those numbers. But the velocity seems way to low.

Hodgdons data says 834 FPS out of a 7.7 test barrel with 3.7 grs HP 38. I do not expect it to be exactly the same but how close should it be??
So over 300 FPS due to a 3.7 difference in Barrel length??


Lyman data shows 767 FPS With 3.6 grains out of a 4" test receiver
and 837 FPS with 4.0 grs

Speer uses a actual SW Model 14, 6" barrel.

Their data is 783 FPS with 3.8 grs W231/HP38 so that has me believing aprox. 100 fps loss per 1" in barrel length if my readings are correct.

Does that sound reasonable??

Is my Chrony Alpha that far off????

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Still Running Against the Wind

Dude, light's hitting the electric eye of your Chrony and fouling up the readings. Put up some homemade shields in front of the electric eyes to keep the glare off them.

This has happened to me with Chrony products since the '80s - putting up the shields always fixes it.

You mean bigger sky screens? My first one would totally go berserk if out in the full FL sun. I tried cardboard, old light diffusers and other junk for that one and nothing worked.

This one does not give any error messages and I waited to later in the day with the Sun behind me and put it in the partial shade given by the shooting bay.

Any suggestions on what to use? I have seen competition ones that are housed in a box with adjustable sides but those are semi permanent.

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Still Running Against the Wind

Just for you to have some comparison numbers, my 4" M66-1 with 13.5 gr 2400 and a 158 gr Oregon Trails LSWC will clock 1257 fps average out of .38 Special brass. That figures 1301 fps MV, which MV may also be what Hodgdon uses for their numbers.

I get virtually the same numbers out of the same gun if I use a Dry Creek 158 gr LSWC (1303 fps MV).

That's a stout 38 special! I just loaded some 357 brass with 12.5 grs of 2400 and the 158 gr LSWC. avg for three string of 10 were 1060, 1035 and 1101 from a MP R8 (M327)

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Still Running Against the Wind

You can use plastic milk jugs for your screen covers.
The eyes see a shadow of the bullet pass over, shiny bullets sometimes don't record well, some have made their bullets black with a Sharpie marker to get better readings.

The amount of light does affect performance on the chrony and the distance to the first screen if too close can be affected by muzzle blast.

Best regards,

Or...buy an Oehler 35 and it simply ALWAYS WORKS.

That load was from Elmer, but intended for a strong gun, i.e N frame or .357.

Hodgdon is pretty notorious for publishing unattainable velocities.

Speer #8 used a 6" K-38 and got 1155 fps with a 158 gr LSWC with 11.0 gr of 2400, but they also used a magnum primer for some odd reason. I think that may be a lot closer to real world results than the majority of what you see now.

Here's the M66-1 I used.

The 10 inch unvented (no barrel cyinder gap) test barrels dont do a lot for real world performance either! Result's do vary.

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Stay safe people!

If the direct rays of sunlight or glare from some other source are falling on the pickups ("eyes"), you are going to have problems, not only with the Chrony, but with all of them.

Chrony says you don't need "skyscreens" when the sky is overcast, or cloudy, but you do when the sky is clear. Their opinion is that it creates a known, uniform "background" for the bullets to be viewed against.

If it isn't too dark already, I use the skyscreens even on days with clouds, and very seldom do I get error messages.

Flash

Assuming that you followed the rule of skyscreens when sunny and no sky screens when cloudy, then......make sure it is completely open, (or you'll get fast velocities), and make sure the Chrony is level to the shot (or you'll get slow velocities).

I had a Chrony that wouldn't read jacketed bullets, sent it back. The next one worked fine until I shot it.

Alpha Master Chrony Info

I'm on my second Alpha master Chrony too. I shot the first one after
moving back to about 25 ft in a vain attempt to get valid readings with
various hand gun loads. Seems that the screens are triggered by the
muzzle blast rather than the bullet on sub sonic shots says the factory
rep I talked to on the phone. Move back he says. The second one is
just as useless as the first. I bought a ProChrono Pal, 99.00, it works.

PMd you back: I don't mean bigger sky screens, I mean put small cardboard shields in front of the electric eyes to keep the sun's glare from hitting them.

Well now, I don't feel so bad. I shot my first Chrony also. My replacement works fine as long as I keep it out of the direct sunlight.

What is this Cloudy you speak off?? Pretty much summer here already 90* and the same humidity. My range is facing E and W so pretty much blasted with solar radiation all day.

As Erich has mentioned it might very well be the reflective light hitting at an angle or "bouncing" off sandy ground like at a beach

Yes, "Screens are Up", unit is level. I have it on a camera tripod with a bubble level.

I'll try taping some cardboard strips in front of the sensors and hopefully get out there today if I finish some painting that SWMBO has put on my list.

If that doesn't work I might just shoot it on purpose!

Thanks.

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Still Running Against the Wind

Sorry, it has been awhile since I've experienced a sunny day - I may not remember it correctly

Another trick you can try is to use the Chrony upside down, looking at a sheet of butcher wrap (or plastic tote lid, etc.). You can also use it sideways (put a little tape on the sky screen rods). But truthfully I think your Chrony is working fine. And yes I think you'll have 300fps with a 3.7" barrel length difference.

Firearms vary. And loads vary. But chronographs don't vary much when setup correctly.

Several are misusing a term here: Shades or diffusers are not skyscreens. Skyscreens are the actual sensors that detect the passage of the bullet overhead. They are referred to as skyscreens because early chronographs used actual wire mesh screening, through which bullets were shot. As one would imagine, repeatedly having to replace the screens was a pain. Skyscreens remedied that, but have their own quirks. They tend to work better on overcast days than sunny ones, and should always be in the shade if it is not overcast. It is especially important that each screen receive the same amount of light, i.e., you don't want to have one in shade and one in sun.

The .38 load you've described sounds mighty puny to me, and since the velocities you've reported are quite consistent, I'm inclined to believe they are fairly close to reality. There is likely to be a very large difference between a 7"+, unvented test barrel and a 4" revolver. Even between two different 4" revolvers, I've seen identical ammo from the same box read 100fps.+ apart. The main difference is in the barrel/cylinder gaps, but bore dimensions and "slickness" vary, also.

Typically, all things being equal (but they never are) you should see more like a 50 fps/inch difference in barrels than a 100 fps/inch difference, but the other variables, especially in revolvers, make it impossible to apply any firm rules. The differences will be greater with slow powders than with fast ones, also.

Good luck with your quest. I've had my own chronograph woes in recent history, and finally had to retire my old PACT Professional. It was either that or drive myself nuts trying to find just the right conditions for it to work. I replaced it with a CED M2, and life is now good. The M2 seems to work in conditions in which it really shouldn't. Hope it lasts!

FWIW, I had a PACT Model 1 for 13 years and it worked perfectly until the electronics board gave up. I replaced it with a Chrony, which gave me bad results on day one. It gave me data that was obviously wrong, and even that data varied all over the place.
I returned to Midway for a refund. The folks at PACT gave me a 30% credit to trade in my old Model 1 for a new one. The new one is warranted for life, unlike the original. It works perfectly.

Yes, you are correct my terminology was incorrect, they are "diffusers" As to the load, 3.7 is the max according to Hodgdon, and I agree they are not noted for "hot loads" they try to remain in the safe zone for everyone camp. Speer has pretty much the same load but their bullet is a softy.

Does your CED have the detached or remote Keypad? That is one feature that I would have to have. I can't or do not want to walk out to the unit to get my data.

Anyway, the Good news I took a 3 fold attack. I just got back from the range so it was about 4pm when I was shooting. The Sun was more behind me so the shadow cast by the range bay was bigger. I set the unit up at 5 ft (a little further than last time and even though it was in shade, I taped up cardboard as Erich suggested.

I test fired some 22LR Rem Golden bullets from a 4" M -63

Avg 909, ES 160, SD 59 (Box says 1200fps)

With Federal Spitfires avg 1153, ES 72, SD 22

(Box says 1500)

No doubt both tested out of a long rifle barrel.

+++++++++++++++++++++++++++++++++++++++

Same loads same gun same shooting bay same 90* temp.

M 67 with 158gr LSWC MBC soft 12 BHN and 3.7 gr HP 38

string 1, Avg 736, ES 92, SD 27
string 2, Avg 760 ES 50 , SD 12

So the velocity jumped up 200 FPS which is more inline as the manual data.

The 357 Mag loads with 12.5 grs 240 and the hard (18 BHN) 158 LSWC out of the MP R8

Jumped up 100 FPS

All loads measured with RCBS Uniflow and spot checked .

So, it sure looks like the Sun Light is the problem.
The Chrony Alpha Master is certainly not the best unit out there but if i can get it to work correctly, it will do for my needs or until I nail it.

Thanks to all for your help.

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Still Running Against the Wind

I used an old Chrony F1 for a long time until I "just barely nicked it" with a 240 gr 44mag bullet at 1400 fps. Did you know that Chrony will give you generous trade in allowance on used Chrony's regardless of condition? I now use a Beta Chrony, and it works just fine. I find having the sun fairly direct overhead (regardless if it is bright or overcast). In other words placing your chrony (or any chronograph) in an orientation so the sun isn't at a drastic angle to the front or rear of the unit. I use the recommended 12-14 ft. from the muzzle to the unit. I find best results with 10 round strings. I have checked my chrony results against a couple other makes and get nearly identical results.

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H Richard
SWCA1967 SWHF244

I didn't know about the trade in allowance. Good to know in case I blast mine. Were did you find 12-14 feet? My destructions say 10 feet for high powered rifles.?

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Still Running Against the Wind

With low velocity hand gun rounds you actually need to be farther back
than you do with high powered rifles because of the muzzle blast
reaching the start screen before the bullet does.

Yup, I found this out the hard way. Now I keep mine out about 15 feet from the muzzle and have no problems with it.

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Andy

Here's a link to the CED M2: CED M2 Chronograph Set

The keypad and readout are in the chronograph unit, which attaches to the skyscreens with two wires, a start wire and a stop wire.


Glad you got the Chrony working.

Thanks, I was looking at their website last night. So that keyboard and screen are sitting on the shooting bench where you are connected by a wire or cable like my Chrony Alpha (it has a phone cable)??

It works well in bright sunlight?

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Still Running Against the Wind

What a great thread. Not the least of which is the shooting of the Chrony. I shot mine 3 times. Twice with a 308 and center punched it with a 45 acp. Worked after the nicks with the rifle. Not so much with the 45. It was a Beta. Worked good. Got the cheapest one next. Not happy. Had the same problem as what started this thread. Did get the thing to work with a 22 lr, About 1150 fps when box said 1200. I think I may have problems with the loads, a 9mm, and the new chrony was working

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old not on active duty Marine

So far, I have used it in every lighting condition one might imagine, other than nighttime. I do plan on getting the IR setup, so I can use it in my barn with my bullet trap, in case I need to chronograph when it is too windy or is raining. (The former happens a lot here, the latter not since last October.) So far, as long as the skyscreens are in the shade and the diffusers are used, it has worked in all lighting conditions. And yes, the chronograph itself is on the "bench" (usually, my pickup tailgate) and the skyscreens are on the tripod downrange.

Thanks. I think it will be my next unit if this Chrony does not work out for me. I was looking at the RCBS (Big Bullet thing) I watched and read a video review on it and it did not fare to well according to that review. It died and looked cheap which is not like RCBS which has great equipment and warranty. Electronics are only one year.

The CED has 2 year warranty the Pact Pro Xp has a "limited" lifetime.

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Still Running Against the Wind

I was torn when I bought the M2. I really wanted an Oehler 35, and they have become scarce and expensive. My old PACT Professional worked well for several years, though it was always a little picky about lighting conditions. I bought new skyscreens for it several years ago, and it did better for awhile, but recently became just too frustrating, requiring just the perfect lighting conditions to work at all. I nearly bought a new generation PACT Pro. I requested information from some compadres on a private forum, and spent a good deal of time on the net looking for reports on the various chronos now available. Mostly, the M2 gets rave reviews. I will say that it is not nearly as intuitive to use as is the PACT Pro. People complain about the instructions that come with the PACT, but it really needs no instructions, since it works so intuitively. The M2 needs good instructions, but its instructions are worse than PACT's. Nonetheless, I am very, very pleased with the fact that I need not wait for perfect lighting conditions to chronograph ammunition, which was the most frustrating thing about the PACT, and about my previous (and first) chronograph, an original Chrony.

In post #27 you mention "as long as the sky-screens are in the shade". That could be part of your problem. If any "shade" drifts over the sky-screens it will affect the reading. You need direct light on the sky-screens. One day I was getting erratic readings, and then I noticed a tall tree and the wind was blowing the shadow of a limb past the sky-screens. As long as I only shot when the shadow didn't drift over the screens I got OK readings.

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H Richard
SWCA1967 SWHF244

My Chrony was so old that it originally came with cardboard diffusers and it always worked great. Last week I put a 44 Special bullet thru it ---- and I'm STILL not sure how I did it. Chrony advertises replacement for $75 --- about the same as Midway charges for the F1 so I bought a new one from Midway. So far it is working great, just as the old one did. I HAVE had the light problem in bright sunlight, but just moving the Chrony around always solved it. I always use the diffusers.

Now lets remember they are "diffusers"

I just got back from the range. Was shooting 44 MAgs. The Chrony Alpha Master was out in direct Sun. Over 100 degrees, not a cloud anywhere

Np error messages and all was well. I thank Erich again for the "tape cardboard around the sensors trick"!

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Still Running Against the Wind