Help Needed with LB3.0 and .338 Bergers

[Pdvdh]

Phorwath's rant is very valid. Now, when it comes to buying a Chronograph let me tell you what Bryan Litz said about that in his book:
I'll be quoting him here.

And then down lower...

If you find an Oehler you'll be paying a whole lot more and for what?... now the M2 is out which is way superior, more sensitive than the former one and for less than $200.00 bucks. Why going back in technology when you can go forward. That's why I got me a CED M2...

Len Backus has written some place also, something similar about the CED and the Oehler. Well... let's just say he's using a CED chronograph.

Just go with your guts feelings though!!!!!!!

Eaglet.
I went with my instincts after having used the Oehler 33s for many years, and reading some recurrent troubling posts on the CED operations reliability on this Forum. To be clear, I have never used a CED. I was preparing to purchase one but then read of too many operations issues by too many users. Some even after having spent the extra money for the CED infrared skyscreens. Then Oehler advertised a 2010 production of their Model 35P. That made my decision pretty easy, and ordered the Oehler.

Oehler's been servicing the US government and industry with premium chronographs for many years. If you read Oehler's web site, you'll read accuracy specifications that are real life. Typical is +/- 0.25% with their 35P and the factory skyscreen spacing. That's in the ball park of what I experience with my current Oehler and PACT. With a 3000 fps MV, that's an error of +/- 7.5 fps. And that error can be reduced with the Oehler 35Ps by running a larger skyscreen separation than the 4' factory spacing. Plenty good for my needs. After accuracy, the second priority is the unit's reliability to obtain a reading on almost every shot. I don't want to place a bullet dead center over the skyscreens at 1000 yds only to find out the velocity was not recorded. I'm giving the nod to the Oehler on that one based on the posts I've read. Lastly, two chronographs are required to be run in tandem to meet my personal goal and needs. The Oehler 35P contains the second proof channel - built in - ready to roll. The alternative is to purchase two other units and hook them together like I have. How much cost savings is there by the time two other units are purchased and fabricated to run as one?

I'm a combination of engineer and home mechanic & welder. Not everyone is interested in fabrication of the skyscreen rail to mate two chronographs into the equivalent of one unit running two chronographs in tandem. So again, the Oehler is ready to run. When mine comes in I'll probably increase the spacing of the primary channel to 6 or 8 feet and run the proof channel at a 3 or 4 foot separation, for an improvement in accuracy compared to the factory 4' primary channel spacing and 2' proof channel spacing. Increasing the skyscreen spacing directly improves the accuracy of any unit, CED or Oehler, because any error associated with the skyscreen spacing is larger with smaller skyscreen spacing. I believe the CEDs are built to operate with a 2' spacing, and there is no provision in the CED software to reset that spacing to 4', 6', or 8', in order to reduce error in skyscreen mounting. A 1/8" error in skyscreen mounting over a 2' separation distance introduces a 0.52% error into the data right from the get-go, even if the chronograph operates perfectly. A 1/8" error in skyscreen mounting with a 8' separation distance produces a 0.13% error in data. With the Oehler, you just reset the setting on the chronograph to match the skyscreen spacing you ultimately decide to operate with. And since the Oehler skyscreens mount on a piece of 1/2" EMT conduit, increasing the skyscreen spacing is as simple and cheap as purchasing a 10' stick of 1/2" EMT and measuring and dimpling the EMT for the desired spacing.

My e-mail communications with CED confirmed that their software did not allow for an increased skyscreen spacing. They told me their model's accuracy was confirmed by an independent tester to be just as good at 2' as it would be at 8' separation. But that doesn't tell the whole of it. That may be true for the electronic processing of the impulses triggered by the skyscreens. But the part that is conveniently overlooked is that a tiny error in skyscreen mounting is magnified with the 2' skyscreen separation distance, no matter the increased clock speed of the electronics or how perfect the rest of the unit functions. A measurement error is a measurement error, and the best way to reduce that inherent error is to increase skyscreen separation distance, IMO.

 

[Pdvdh]

Would this all be avoided if we would shoot and gather MV data at several different yardages and use the Analyzer feature to calculate the true BC and DC for that particular rifle and bullet. I think this is a valuable feature of Loadbase that may not get used much.
I think that two proven chronographs or one Oehler 35p with the proof channel is the way to go as Phorwath has high lighted in his work with Loadbase.

I was wondering about the accuracy of our predicted trajectory when we tweek numbers and then move to a way different environment, it makes me feel uneasy about what I'm getting when I know I had to fudge something up front, even if it matched on that day.

bigngreen,
I've been there and done that method twice. The chronographing of velocity at four separate distances and running the numbers though the LB Analyzer Module. It's a lot of work. That was before Bryan came out with the G7 BCs and before LB software was enhanced to operate with G7 BCs. One of my two efforts resulted in dead-nutz-on predicted dope. The other effort was off a bit. I concluded it's awfully time consuming and requires a number of shots at each distance over proven chronographs to give it the honest college try.

I also concluded that there's a less time consuming approach to ensuring MV, BC, and DC input values are accurate. My approach is to work up a load with the chronographs recording MV and my target at 300 yds. By the time you've worked up an accurate load that also has sufficiently low ES & SD, you'll know with high confidence what the MV is, and you'll know with high confidence that vertical stringing should not be an issue due to excessive ES/SD. Next prove the load's accuracy at long range. I've never been surprised yet with an accurate load at 300 yds not performing at 900-1000 yds. Not to say it couldn't happen. Just that I haven't experienced that issue yet.

Now, after shooting at ~1000yds enough to confirm accuracy is acceptable, and to determine point of impact, I shoot over the chronographs at ~1000yds. Then I use LB to predict the 1000 yd velocity with the published bullet BC and see whether my measured velocity is high, low, or a perfect match. So far with the three Bryan Litz G7 BC rated bullets I've tested, I haven't had to make any refinements to DC with the LB software. Measured 1000yd velocity matched predicted velocity to within the accuracy of my chronographs.

However, if I measure a 1000yd velocity substantially different (more than ~10 fps) than the predicted LB 1000yd velocity (before the Bryan Litz G7 BCs I did experience some disagreement with the former Berger G1 BCs and Nosler Accubond G1 BCs) I will then tweak the DC in LB3 until the LB predicted 1000yd velocity matches my measured 1000yd velocity. I don't see how one could do much better than this for the time and effort involved. Even if one distrusts the absolute accuracy of the measured velocity, there's little reason to doubt the accuracy of the difference between the 1000yd velocity and the MV. Because if the chronographs read a little slower or faster than the true velocity at the muzzle, they are almost certain to register a 1000yd velocity equally slower or faster than the true velocity. And since BC is based on the difference of the velocities to a much much much (almost entirely) greater degree than the absolutely correct MV or 1000yd velocity, there's every reason to believe that using my process will result in the identification of the DC that very closely matches the actual drag curve of the bullet across that 1000yd distance. By jumping straight out to 1000yds, I also minimize the affect of any error in the chronographed velocity data. A 5fps measurement error while determining BC with a 1500 fps loss of velocity over this 1000yd distance introduces much less error than the same 5fps measurement error over a 200 fps loss of velocity over a 100yd distance. The measurement error or accuracy of the chronographs is what it is. But I largely negate the affect of that measurement error by shooting over such a long distance that any measurement error becomes inconsequential, relative to the total reduction in bullet velocity.

That's the way I see it, and that's the way I do it. In my opinion and experience, this method produces a completely satisfactory result with much less time and effort in the field than going through the labor intensive process of measuring velocity data at four different ranges and then running that data through LB3 in order to determine a BC and DC.

And it's a much more valid approach than guessing either the BC, MV, or both, in the effort to make field drops match ballistic software predicted drops.

I had just about decided Bryan's G7 BCs were good to go and now he experienced a blooper with the .338 Berger G7 BC. This incident simply confirms that to error is human. The incident also serves to demonstrate the pertinence of my process in order to validate the accuracy of the BC, DC, and MV input values for any ballistics software program. Good data in = good predicted dope out - under any new set of environmental/atmospheric conditions.

The other alternative doesn't need repeating.

 

[Eaglet]

Phorwath,

I will agree to disagree... Just kidding!!! Every point you brought our is very well expressed and I agree with it. I fully understand your concerns about the need to have a reading every time and the need to have them measurements right on the money. No arguments from me.

On the other hand I would like to express that like you, before I bought my CED chronograph I read about both chronographs in question, I read and got all the info I could until I would fall sleep. Oehler has been the daddy of all chronographs from my readings.

To my understanding they're not being made any more, and the CED is very fast taking its place.

I have never owned one but I have owned three CED's, two regular millenniums and the last one the M2. Have read just about every complaint that you mentioned. Based on my experience and my heavy use of these chronographs, none of them have been exposed to 1000 yards , I can testify how rarely I have had a "no-reading", I believe folks are not reading their user manuals.

Your post is very informative and I had already thought about Bryan's writings when he mentions in his book that 1/32" error in 2' apart screen spacing as the CED has would produce an error of about 47 fps for a bullet traveling at 3000 fps. On the other hand, the same 1/32 error in 8' apart screens would only result in 11 fps error. Pretty amazing and understandable. He was concerned about this fact and set up both units, the Oehler and the CED in tandem and after some repetitions of the test both units agreed within 8 fps. His deductions were that both units were capable of the same accuracy. On top of all that, he, Bryan, equipped the CED with infrared screens that effectively makes the unit immune to errors caused by ambient lighting. All this to say "The CED's are Very Accurate and Reliable".

So much for accuracy. Now aside from that, the technology on the mother board of the CED is definitely superior to the old Oehler.

A person can not go wrong with either unit. I just can't afford the more expensive one and I'm glad I can get the quality for less money. Not that I'm cheap, I just can't afford it!! Really!!!

One more last thing, down below is an image of a post that I love to use when I have these types of conversations...

In any event, I tip my hat off to you and you will not have any complaints from me for using an Oehler.

Thanks for posting!

 

[Eaglet]

I had just about decided Bryan's G7 BCs were good to go and now he experienced a blooper with the .338 Berger G7 BC. This incident simply confirms that to error is human. The incident also serves to demonstrate the pertinence of my process in order to validate the accuracy of the BC, DC, and MV input values for any ballistics software program. Good data in = good predicted dope out - under any new set of environmental/atmospheric conditions.

Do you think it is possible the the bullets you used do indeed have the BC7 of 0.455 that was given first?

Is it possible that, since they're still ironing all the wrinkles out, some how along the way due to production procedures the BC changed. I trust the work you do and that's the reason I'm asking these questions.

 

[Broz]

I'm late... spent time with the mechanic working on my Trooper and took the wife to dinner and before that bought some parts for my vehicle...

Broz, you're playing the game!!! That's alright!

In the results below you're giving a little more preference to higher velocity and I'm sticking a little longer with the BC...
I guess either one can be used.
I'm being... Interpolating a bit for the last two... you know between the 5's

2660?? I'll plug in some numbers but I betting you mean 2760?

Its calm out this am. I am going to test this in a bit.

Jeff

 

[Broz]

OK, just shot 5 more with Eaglet new numbers. I did use 2760 for MV though 8 3/8" high at 1182 yards. Keep in mind LB would only let me enter 1180 or 1185, so I used 1180.

FC was

Temp 56*
Baro 25.89
hum 30%
distance 1182 yd

Disclaimer: I was not shooting my best. Second one missed the target but was right there. Sun was rising behind the target and I had glare in the scope. The left was from a slight 45* (3 oclock) thermal wind between me and the target, I believe. I didn't switch it on but corialis was 90* (east) and 46* lat.

I feel this is very solid info I was prone on concrete just out of th garage door. I had to go up and chase the elk away from the target befor e could shoot though.. Life is good...

Jeff gun)gun)

 

[Broz]

Just figured out most of the shooting left thing. As stated above I entered 45* for a 3 oclock wind... If I had entered correctly 90* for the 2 to 3 mph wind at 3 oclock I would have been with in a click for windage. Arrrh! That degree thing is going to get me. I migh have to make up some flash cards and practise..

Jeff

 

[bigbuck]

OK, just shot 5 more with Eaglet new numbers. I did use 2760 for MV though * 3/8" high at 1182 yards. Keep in mind LB would only let me enter 1180 or 1185, so I used 1180.

FC was

Temp 56*
Baro 25.89
hum 30%
distance 1182 yd

Disclaimer: I was not shooting my best. Second one missed the target but was right there. Sun was rising behind the target and I had glare in the scope. The left was from a slight 45* (3 oclock) thermal wind between me and the target, I believe. I didn't switch it on but corialis was 90* (east) and 46* lat.

I feel this is very solid info I was prone on concrete just out of th garage door. I had to go up and chase the elk away from the target befor e could shoot though.. Life is good...

Jeff gun)gun)

1180 yrds "just out of the garage door" and you had to "go up and chase the elk away from the target " .......... I'm JEALOUS !!!

Good shooting and thanks for posting pics of the target.

BigBuck

 

[bigngreen]

Broz, lookn good!! I entered the new numbers and turned on Coriolis and it dropped you .2 MOA and .5 MOA left windage, add in a 3mph wind drift and you need 1MOA right including Coriolis. You'll have it dialed in soon I think.

Phorwath, thanks for the info and thoughts on calculating the BC with Loadbase.

 

[Broz]

LOL, yeah I know... I truely am living good. Not much money, but that stuff is over rated anyway.

I think the one that was off the steel was right in the grp of 3. So if I would not have screwed up with that high one??? Oh well, I might b asking for too much. Happiness is a true 1/2 moa rifle..

Jeff gun)gun)

 

[Broz]

Hmmmmmmmmm. Just noticed that if I use .419 G7 bc , eaglets .495 DC and up the velocity to what I feel is correct 2780, then apply the coriolis for these shots. Things are lookin pretty good as a whole for 700, 1042, 1182, and 1342. I just need to shoot more..

Jeff

 

[bigngreen]

I think that Loadbase 3.0 is such a good program that when you get all the data and it is accurate, then use all the tools it has it will blow the doors of everything else out there that is available to the average shooter.

Eaglet made a little program that you can down load that has all kinds of little tools that I have been using to refine the numbers I have been using in Loadbase.

http://www.longrangehunting.com/forums/f19/small-contribution-shooting-community-55493/

 

[Pdvdh]

Phorwath,

I will agree to disagree... Just kidding!!! Every point you brought our is very well expressed and I agree with it. I fully understand your concerns about the need to have a reading every time and the need to have them measurements right on the money. No arguments from me.

On the other hand I would like to express that like you, before I bought my CED chronograph I read about both chronographs in question, I read and got all the info I could until I would fall sleep. Oehler has been the daddy of all chronographs from my readings.

To my understanding they're not being made any more, and the CED is very fast taking its place.

I have never owned one but I have owned three CED's, two regular millenniums and the last one the M2. Have read just about every complaint that you mentioned. Based on my experience and my heavy use of these chronographs, none of them have been exposed to 1000 yards , I can testify how rarely I have had a "no-reading", I believe folks are not reading their user manuals.

Your post is very informative and I had already thought about Bryan's writings when he mentions in his book that 1/32" error in 2' apart screen spacing as the CED has would produce an error of about 47 fps for a bullet traveling at 3000 fps. On the other hand, the same 1/32 error in 8' apart screens would only result in 11 fps error. Pretty amazing and understandable. He was concerned about this fact and set up both units, the Oehler and the CED in tandem and after some repetitions of the test both units agreed within 8 fps. His deductions were that both units were capable of the same accuracy. On top of all that, he, Bryan, equipped the CED with infrared screens that effectively makes the unit immune to errors caused by ambient lighting. All this to say "The CED's are Very Accurate and Reliable".

So much for accuracy. Now aside from that, the technology on the mother board of the CED is definitely superior to the old Oehler.

A person can not go wrong with either unit. I just can't afford the more expensive one and I'm glad I can get the quality for less money. Not that I'm cheap, I just can't afford it!! Really!!!

One more last thing, down below is an image of a post that I love to use when I have these types of conversations...

In any event, I tip my hat off to you and you will not have any complaints from me for using an Oehler.

Thanks for posting!

Eaglet,
I presumed you would do the research prior to investing in your chronographs. Good for you. And I did read your posts of the flawless operations you've experienced with the CED MII. I just became bothered by some of the snags others were running into, and I know how aggravating those issues can be. Been there done that myself.

Russ Hatch,
I had read the CED literature you posted prior to making my decision. You can bet that before CED spent the money to have their units tested by the German firm, that they ensured those units were 100% functional and as close to perfectly set up as is humanly possible. Not knocking them for doing that. It only makes sense that the units being tested are functioning 100% as intended.

Anyhow, I'm not really here to pump chronographs. My posts simply consisted of some of my observations and conclusions. So don't take my posts out-of-context in that manner. I hadn't read that section of Bryan's book Eaglet referenced, but it sounds like Bryan touched on the concern I expressed about skyscreen spacing. The chrono simply processes the signal from the skyscreens. It doesn't know or care if that skyscreen spacing is correct or incorrect. The chrono will provided a reading based on the actual skyscreen separation.

I hope that CED continues to compete in this market successfully, as competition does generally drive innovation, technology, and improvements in quality. And Oehler hasn't manufactured their layman's version chronograph for quite some time now. If CED can fill those vacant shoes, more power to them.

 

[Broz]

Well, this isn't so different from when I was racing. More than one way to skin the cat and more than one will work.

I am not sure there is a "perfect BC" or a true Chrono reading. I have just learned that even Oehler will tell you a sunny day could make even "the Best" chrono read 20 to 30 FPS fast.

The thing I have learned is, you need to shoot, a lot, and at different distances. Just by doing this you can fine tune all the numbers. The more you shoot the more you will see what you yourself as a shooter needs, to be effective. That and trigger time will let you know what your effective range is.

Jeff