Ok, got my F1 Chrony working at the range near my house. Its covered, so I had trouble getting required light. So I purchased the printer. And was able to push out to the max for a little sunshine.

First off, I shot two fouling shots with factory Rem. 180gr Sirroccos just to get rid of those things and get my brass. They read 3800 adn 3900fps out of my 300RUM. Ok, now I know this is BS. So next cease fire, I put up the screens and all. Now it reads more about the way it should be. I get 3200fps but it only reads about 60% of the time. For instance for 93gr of H1000 and 180 partitions, I get 3 readings of 3130fps +/- 9fps. Then I got an oddball 3200fps?

So I move up to 94gr, and get 3150fps +/- 10fps for 6 shots and then get an oddball 3120fps. Ok, I am not sure what to believe at this point, since all my groups were less than 1.2" at 200 yards.

So I did the scotch tape trick over the photocells, and now reads more consistently working 90% of the time but now all velocitys go down for 93gr and 94gr of H1000 about 20fps. But still get the oddball velocities from time to time. Now this is brand new brass that I did FL size before loading.

1. Why would the tape slow the velocities down or just coincidences? I understand why it works cause it filters the spartic light more.

2. With accuracy like that do you think those oddball velocities are real? I mean some deviated 70fps from the average. Is this normal? Should my extreame spreads be so wide?

3. Could it just be the weather that day. Very cloudy, not much light.

Any help would be appreciated.

Big, your not getting "oddball" readings. It is not uncommon to have vel. spreads of 100fps or more? What you strive for are those small, less than 30fps spreads you are showing. Your groups are small & consistant & your vel. spreads,+/- 10fps are great. The larger powder cap. rounds will often show larger swings in vel. I see this more w/ my 7mm Dakota than my .280. Some times the loads w/ the smallest deviation are not always the most accurate. It sounds like everything is working fine.

I have a Pact chrono. & use the scotch taped sky screens to eliminate the "oddball" vel. reading. I'm talking 1000fps diff., that's a problem! This only seems to happen on very bright, high noon type days. Overcast days seem to work best for consistant readings for me. If you are in doubt about the accuracy, check it w/ a known load. I like to use match .45acp ammo from my 5" Govt. mdl. Good shooting!

[ 06-10-2003, 04:32: Message edited by: fredj338 ]

Well thanks. Would like to compare with another chrony. With 94gr of H1000 it was shooting exactly what Nosler publishes which was 3160fps. Just those oddball ones got my attention. Especially with 3800fps readings.

Yes a 3800fps is definetly an attention getter. Like I said, I have had some blips that show my 7mm Dakota going 1850fps when I know damn well it's doing 3250fps! That's when I got the tip for the scotch tape. That & staying out of the dirrect overhead, bright sun has helped the consistancy alot. When in doubt, check it w/ some really consistant pistol ammo. I like to use that because there seems to be a smaller window of error from gun to gun.

I do something like that. I use my bow. I know it always shoots 260fps +/-8fps or so. just an idea if you don't want to wake up the neighbors.

...you didn't have it opened all the way up... thereby reducing the distance between sensors... and making it "look" like it was going faster than it was....

50-100 fps isn't oddball, but not great for +/- consistancy
jeffe

No, I don't think that was it. If you do the math on these chronographs, the tolerances by not opening all the way way is almost a moot point. Especially with the crystals they use to count the cycles.

BC,

I owned two of them before I broke down and bought the Oehlers. If one edge hits the tripod mont and it fails to open up all the way, you "will" get higher readings. How far it keeps it from opening up all the way will vary with the tripod mount though. How far off the MV is will "also" depend on how far above the screens the bullets are passing over them. Same problem results with it not being paralell to the bore line too.

The short screen distance of the Chronies will make it worse too.

From your results, I'll say this; You are getting great reading so far. Sometimes they can be quite accurate and then they go to hell, alot worse than yours is too. You can do a test to see if the tape is actually responsible for the slower MV.

This is the main reason I tanked the Chronies and went and got an Oehler, i was tired of playin with the damn Chrony and not my loads. You're startin to feel the frustration... trust me, it don't get better either.

I just checked my average MV with my 300 Ultra for the fourth time with a load of 88gr RL22 and a 178 AMAX. It was 3228 fps........ all four times on seperate days too. Now that's what I'm talkin about! How much is the frustration and your "time" screwing with the chrony "worth", that's what you have to ask yourself I'm afraid...

Good luck with it, I hate to say how different the reading were between the two I had when setting in front of each other. Suffice to say they switched around all over and 200 fps difference at times didn't instill confidence at all. FWIW

No chronograph is perfect, not even Oehler.

Short screen spacing and very shiny polished bullets only makes matters worse. Next time try this trick: blacken the bullet with a magic marker or some other means. Don't worry about perfection, just mark most of the fattest part of the bullet. Your screens will be more able to 'see' the dark spot against the sky rather than the 'glint' or sparkle as it whizzes over your screens. Its the contrast of dark against light that makes the difference.

I have to go with Brent on the Oehler. I've been shooting over a Beta Master Crony and finally ordered an Oehler 35 with the 4 foot rail today. I should have it before my newly remodeled range opens back up.

[ 06-14-2003, 21:24: Message edited by: SST ]

onefunzr2,

Typing is not one of my strong suits. When I hunt and peck without my reading glasses, the results can sometimes be quite comical. As for the "I have to go with Brent", I was referring to moving up to Oehler equipment, not any particular model.

I guess I'll edit out my 4 inch rail.

[ 06-14-2003, 21:25: Message edited by: SST ]

Dave,

I do use my 43 mainly, but it's just because it keeps track of my data without rewrighting it and it measures psi too. They both do the same great job as far as MV is concerned. It use the same 4' rail and screens as my 35P does. I just use the 35P when I'm out on the 4-wheeler, as I have it all tucked away in a Starlight case.

The reason Oehlers haven't came down in price as tech has increased, is they still have the best and it doesn't get any better anyway. IMHO they should all be a hundred bucks but the competition isn't there so why drop their price... An updated and collapsable 4' rail system, a padded hardcase, USB port with supporting viewing and data filing program and a transfer ability to the Ballistic Explorer program of theirs like the 43 can, those would be nice upgrades. Include all that and the Ballistic Explorer program for about $350.

Bigcountry
try this, if you like.

Set your chrony up, and shoot 3 rounds over it... make sure it's all the way open

then take 4 2" square skims from a coke can, and put them, adding, 1 at a time for 3 shots each.

Then see how FAR off then .01" made in shortening that.

The vector change is critical over TIME, which is how these gated chronies work.

cheers
jeffe

It seems that that .300 RUM is burning a lot of powder to get only +-3100 FPS!! My .308 Norma does 3180 with 78 grains of H4831 with the 180 NPJ!!

Please Eld, we have heard you talk for over two years now in a few different forums on how you don't like this cartridge. As you know, it all depends on how fast the powder is and the brass. I can drop to a different powder like 4350 and use alot less powder. But amount of powder doesn't really matter to me that much as long as its accurate, and decently fast. I am sure your using Norma brass, which I find I have to drop my loads 2gr in some cases, with this quality brass. But they don't make it yet for the Ultra Mag. If your going to make a comparison, you got to be fair.

Anyway, I figured out it was the weather that day. This weekend, I had alot more light, and it read alot more consistently. Also, I was trying out 180gr Grand Slams, and was reading 3325fps with 93gr of H1000 compared to 3100fps with 94gr of H1000 with 180 Noslers. Has anyone ever seen where the grand slam builds up alot more pressure than Noslers?

Come on guys, oehler???????? Didn't you guys know that the US is in a recesssion. You guys need to get me a job to be able to buy that million dollar chrony.

[ 06-16-2003, 22:03: Message edited by: bigcountry ]

BC,

How much did you pay for the last descent rifle scope... 200-350 I'm guessing? You didn't buy it for the quality and repeatability too?

How about the last rifle?

I wish someone had urged me to buy an Oehler years ago, would have saved me time, money and frustration... which would have been well worth the price Oehler asks for their base unit... at the very least.

Good luck with your Chrony.

In this economy, I ain't buyin rifles or scopes either