Oehler 35P Questions

[SHRTSHTR]

I have had my Oehler for about a year now and have a couple questions for the Pro's.
I am getting different velocitiess from the two screens on my Oehler. When I do a print out of my shot strings the left collum velocities do not come close to my right collum Velocities. The right collum numbers range from 20-40fps faster.

My Oehler came with a 4ft piece of conduit with three dimples to attach everthing. I usually measure 12ft. from muzzle to the 1st screen. I am thinking my spacing maybe off a little or I need a longer bar to hold the screens. I do not think there is anything wrong with the unit...just the operator Suggestions Please.

P.S. I am shooting a 338LM & 300WM with Muzzle Brakes.

 

[BountyHunter]

call Oehler they will set you straight and they still service the 35Ps.

http://www.oehler-research.com/

BH

 

[Broz]

I don't spend much time with chronys, both of mine are cheapies and I have yet to see one I trust. How is your verticle spread at 1000 yards? Proof is in the pudding...

gun)gun)

 

[laportecharlie]

A couple of things come to mind: Your chrono may be measuring muzzle blast. To avoid this shoot through a hole in a piece of plywood. This acts as a baffle. Second, make sure your chrono is set for a four foot span. There are some dip switches inside the unit. Confirm they are set for four feet. This is explained in the manual.
Charlie

 

[SHRTSHTR]

Thanks Guys,

I am not having a problem with ES or SD. I am having a problem with the bullet passing through the 1st screen and the proof screen....this is where my variance in velocity is coming from. I would like to setup my Chono with a 8 ft. spread. I think this would be more accurate. If anyone has done this I would like to hear about it.

"Laportecharlie"

I do have my dip switches set for 4ft. I like the idea of plywood in front of the muzzle to avoid muzzle blast.

 

[Broz]

I suspect that 12' is not enough to clear the muzzle blast. Last time I had trouble with ES in the 40's fps from my chrony I moved it out to about 18 to 20' and it calmed down. Or the plywood is a great ides too.

Jef

 

[SHRTSHTR]

Thanks for the info Jeff

I only use the Chrono for initial load work up. I learned from someone to see how the load does at distance.

 

[Mikecr]

Never understood how a 'proof' channel is an advantage... IT DOESN'T PROVE, OR DISPROVE, ANYTHING!
With it, your just challenged to get two chronographs perfectly set up, instead of one.
If this proofing is important to you, then you need to calibrate proof to primaries with tweaking (like rail level).

 

[SHRTSHTR]

Mikecr,

Now that is funny stuff right there! I have wondered about this very thing. I have heard great things about Oehler and that Is why I bought one. No problem getting steady readings from the 1st screen...just bugs me about the 2nd screen readings. No big deal, I will try setting up a little different and see how it works outs.

Thanks everyone!

Ray

 

[Pdvdh]

Never understood how a 'proof' channel is an advantage... IT DOESN'T PROVE, OR DISPROVE, ANYTHING!
With it, your just challenged to get two chronographs perfectly set up, instead of one.
If this proofing is important to you, then you need to calibrate proof to primaries with tweaking (like rail level).

Your position surprises me. Do you not understand the advantages? Or do you understand the advantages but not value those advantages? I suppose it really depends on one's purpose(s) for chronographing loads relative to the level of time and effort one is willing to invest in the process. Running the second chronograph in tandem requires no more additional time than to set the second unit down next to the first, and stringing the extra set of cables to it. My two sets of skyscreens are permanently mounted on a 6' long rail.

I articulate, as well as demonstrate, advantages of concurrently running a second chronograph in tandem in the following posts/threads. "Jon A" does likewise in the last of the below links. If you read these posts/threads and still don't understand the advantage, then it is probably more a matter that in your opinion chronographs aren't worth the fuss, and they likely haven't found a place in your load development and LRH toolbox.

http://www.longrangehunting.com/forums/f19/280-ai-replacement-270-win-43784/index12.html

http://www.longrangehunting.com/forums/f19/es-sd-54377/

http://www.longrangehunting.com/forums/f19/loadbase-3-0-mobile-w-g7-bc-test-results-46812/

http://www.longrangehunting.com/forums/f17/best-west-really-best-47550/index17.html#post343178

 

[Mikecr]

I don't understand, value, or use the proof channel.
IMO, comparing expected +/- errors to each other only leaves a wondering of which chrono is 'most' correct. Proving nothing..


I'm satisfied using the Oehler 35P without the hype, thank you.
My screen spacing is 20', and my velocities are as expected with little fuss.

 

[Pdvdh]

I don't understand, value, or use the proof channel.
IMO, comparing expected +/- errors to each other only leaves a wondering of which chrono is 'most' correct. Proving nothing..


I'm satisfied using the Oehler 35P without the hype, thank you.
My screen spacing is 20', and my velocities are as expected with little fuss.

There's nothing to thank me for. I've pointed out the advantages, and you're honest enough to state that you don't understand them or value them. Your mind is yours alone and thank God in this country we can think as we please. I don't pretend, or care, to modify your level of contentment with your single Chrono setup. You get a velocity and you're content with that number without any means of verifying the operational integrity of your unit; and thus the credibility of that velocity. If the velocity's in the ball park and as you expected, you're good to go. You've confirmed a bullet left the bore and travelled over your skyscreens. What more could a guy want? Perhaps most importantly, you're proud to operate an Oehler 35P with that 20' spacing and there's no reason to fix a method that isn't broke. If it's been good for the past 15 years it's clearly good enough for the next 15 years. You don't need any smart alec advice - especially in a public Forum.

I'm willing to take the extra 5 minutes and end up with a means of verifying the operational integrity and reliability of my instruments, obtaining a means of data validation with the second, independent chronograph. Because when the credibility of the data has been brought into question by an anomalous delta of the velocity differences, I can qualify or dismiss potentially flawed data, thereby ensuring data sets of verifiably high quality. When I obtain a low ES/SD load, I can be confident that load won't string vertically at long range due to variable MV. This second chrono reduces the blind faith reliance on a number from a single operable unit.

But what the hey? It's an Oehler and you obtain velocities that are in the ballpark. Besides, what would a guy like me have to offer you? The world surely looks grand from your throne, gazing across that 20' skyscreen spacing. Hope I didn't hurt your feelings... too much.

This post, although in response to your reply, is now for the benefit of other Forum members less set in their ways, that might have the interest in improving the level of quality assurance and quality control of their chronographed velocity data, and employing a relatively straightforward method of obtaining verifiably valid ES/SD of their LRH loads.

 

[LRHWAL]

SHRTSHTR

You haven't indicated whether the variation between the screens is identified by your 35P as an "error". If you use the printer there will be a star alongside the reading, without a printer the display will flash. That indicates to you that the system believes that your error is great enough to "worry about".

I don't recall, but I've seen somewhere that some chronies can have acuracy only with on +/- 1 to 1.5%. That's easliy your 40 fps.

I suggest you check your spacing. Test it one way. Then turn the rail around and swap the start and stop cables. The mid is still the mid. If your fast reading and slower one swap around it's very likely your screen spacing. This would probalby be the case too if you consistently have the variation and on the same set of screens. That said, I haven't looked at the way it reads and don't recall which reading the proff channel reads (i.e. mid and start or stop).

I like the proof idea.

If like MikeCR you don't think it adds anything you can adjust the switches in the unit to ignore the proof channel.

E-mail Oehler and get an instruction manual e-mailed to you. Their support is great. My questions over the years have always been promptly answered. I've just ordered and received some spares all shipped and neatly packed from Oehler in the USA to me in Africa.

 

[SHRTSHTR]

LRHWAL,

Sorry about the late reply, have not been around the last couple of days. You have actually touched on the very questions I had and the reason I started this thread in the 1st place. I will try and answer as best I can.

"Quote"
You haven't indicated whether the variation between the screens is identified by your 35P as an "error". If you use the printer there will be a star alongside the reading, without a printer the display will flash. That indicates to you that the system believes that your error is great enough to "worry about".

I am not usually getting any errors * on my print out. Just veloscity variances. Maybe the numbers I am getting are within the tolerances of the unit, but this is what I am questioning in the 1st place. Here are some numbers from old printouts I saved. Maybe someone can tell me if the spread I am seeing between the 1st screen and the prof screen seems normal.

Oehler Print Out:
2746-01-2738
2711-02-2711
2724-03-2714
2736-04-2721
2747-05-2734

05-2738-+ (Max Velocity)
05-2711-- (Low Velocity)
05-0027-T (ES)
05-2723-M (Average Velocity)
05-0011-$ (SD)

Here's one more:
2761-01-2749
2772-02-2760
2752-03-2738
2750-04-2736
2753-05-2743

05-2760-+
05-2736--
05-0024-T
05-2745-M
05-0009-S

The readings from the Right collum on both shot strings is what I have based my findings on and is what I go by. The first collum is what I understand as the proof velocity and validation of the second collum velocitys.

My rail is 4ft. and I assume that the velocitys differences from Left collum & Right collum numbers should be closer. Once again, I am assuming and these numbers might be normal. If they are normal, I do not see how they are of any use to me. Maybe someone can explain this?

LRHWAL,

I will try your suggestions of flipping rail, placing unit further out and using a level. I do have a manual, found it under foam in case.

Ray