Help Needed with LB3.0 and .338 Bergers

[Pdvdh]

MV = 2710
G7 BC = 0.419
DC = 0.870

Yields:
0.0 moa @ -> 300 yds
10.9 moa @->700yds
22.55 moa @ 1042yds
34.6 moa @->1342yds

That's the best I could do to model the trajectory provided in the initial Post, using the provided atmospheric conditions with coriolis and spin drift turned on. That MV is likely low, and the DC has been modified quite a bit which raises the red flag. This is a bit like a dog chasing its tail, and is why I prefer nailing down the MV. We're guessing on both the MV and the DC/BC in order to build a LB predicted trajectory to match the measured trajectory at these four yardages.

If I use the revised Berger G7 BC = 0.419 and a DC = 0.500, I can't closely match the drops/trajectory no matter which MV I use. The 1042 yd POI seems to require a higher BC than the 0.419 in order to match with the 700 and 1342yd POIs. The best MV match using a G7 BC = 0.419 and a DC = 0.500 is approximately 2742 fps.

Chronograph that puppy!

 

[Eaglet]

Phorwarth,

Did I miss some place the Latitude and Azimuth he was using?

 

[Pdvdh]

Eaglet,

In Post #48, Broz stated "coriolis was 90* (east) and 46* lat" and I presumed those were applicable to the drop data from his first post.

 

[Eaglet]

Thanks!

 

[Eaglet]

MV = 2710
G7 BC = 0.419
DC = 0.870

Yields:
0.0 moa @ -> 300 yds
10.9 moa @->700yds
22.55 moa @ 1042yds
34.6 moa @->1342yds

That's the best I could do to model the trajectory provided in the initial Post, using the provided atmospheric conditions with Coriolis and spin drift turned on. That MV is likely low, and the DC has been modified quite a bit which raises the red flag. This is a bit like a dog chasing its tail, and is why I prefer nailing down the MV. We're guessing on both the MV and the DC/BC in order to build a LB predicted trajectory to match the measured trajectory at these four yardages.

If I use the revised Berger G7 BC = 0.419 and a DC = 0.500, I can't closely match the drops/trajectory no matter which MV I use. The 1042 yd POI seems to require a higher BC than the 0.419 in order to match with the 700 and 1342yd POIs. The best MV match using a G7 BC = 0.419 and a DC = 0.500 is approximately 2742 fps.

Chronograph that puppy!

Interesting, the DC is saying that something is not quite right with the BC... That brings me back to my guts feelings... Shawn Carlock did some shooting and never complained about the BC for them bullets to be off... you thought they were pretty much on, right? Well this is my thing:

Coriolis and SD are ON
SF = 1.63
MV = 2705
BC7 = 0.455
DC = 0.500
Running the application using the appropiate conditions and winds etc.
this is what I get:

300 yards -------0.0 ------
700 yards -------1.5" high
1042 yards -----2.2" low
1342 yards -----0.0 -------

With those results I'd be a happy camper!!!!!!!!!!!!!! I think your results up above, (Good job as a matter of fact) vindicates the results I get.
When BC = 0.455 DC= is happy at 0.500 and look at the velocities... 2710 and 2705.... another thing, I understand that the EdGe is a bit faster than the LM... This is just an idea, 94 grains of H100 get you about 2825 with the EDGE
I would guess 91.5 would bing it down to 2760 fps... with 30" barrel. The rifle in question has 27.5" which is about 2.5*25 = 62 fps less.... Then 2760 -62 = About 2700... Just me talking here; but would kind of make sense. Thats why
I had said that before. Finally Using 0.455 is easy to make the curve match, using 0.419 it just won close.....

When Broz gets tired and frustraded using the 0.419 BC7, he should go back to my above figures and he'll be a happy man!!!!!!!

 

[bigngreen]

Not having a nailed down BC really screws up things, and not having a nailed down BC and MV is shooting in the dark it seems.
Good thing is that the way that thing is shooting the bullets must be stable and not slumping. There seems to be a good case for using the original BC and the lower MV.

 

[Broz]

When Broz gets tired and frustraded using the 0.419 BC7, he should go back to my above figures and he'll be a happy man!!!!!!!

You sound like you know me well.

But here is my take, for what it is worth. I have been shooting this rifle for 3 years now and have close to 800 rounds through it. All this time have been with 300 smk's and I have chronoed it several times. Once on an oehler with a 92.5 gr load of H-1000. I can't remember exactly but I do remember it was lower than my chrono and I dont remember any red flag that day. I mean, if it only showed 2710 velocity I would have been alarmed and surprised. I think I remember 28 something which was par for the course on my exbal program.
In short, I in no way feel that 2710 or less for velocity is accurate and I realize that I do need to get to an accurate chrono (oehler if possible) and see for sure.

Yesterday alone I shot 4 distances all in the same direction. So if this azmuth and coriolis thing really brings something to the table we can use 90* east and lattitude of 46*.

Here is the dope from yesterday.

FC was all the same with the exception of temp I will note that with each shot.
Baro for all was 25.75
humidity 30

700 yards temp 68 10.75 moa needed
995 yards temp 59 20.00 moa needed
1182 yards temp 65 27.25 moa needed
1395 yards temp 61 36.00 moa used, one shot, 2" high

Just for the sake of testing for the 1395 shot I left the windage at zero. It was dead calm both at the gun and target. These perfect conditions prompted me to gather data. With no wind, no spin drift added I hit dead center. Sure it was only one cold bore shot but I feel confident I could have shot two more and held 1/2 moa or very close.

Guys, I am sorry, but I am slipping away here. The LB on my pda takes sooo long to give answers. I have to page back and forth to data tabs, wind tabs, drift tabs, environment tabs and shoot tabs. Some pages take 30 seconds or more to open. I feel this all is great for at home work but not for hunting and this concerns me.

Late last night I loaded Bryans new G1 BC of .818 in my Nightforce exbal program. This with a velocity of 2795 gives me spot on elevation corrections for all the above listed distances and conditions I shot yesterday. Right down to the 1395 it calls for 35.75 moa.

I am feeling that my time will be better spent learning my rifle and what it needs for windage to be effective at long distances. The simplicity ond the much faster results from Exbal keeps pulling me back.

Like I said before, maybe my lack of computer skills and math is the problem and I need to accept that.

The great news is I feel I have gained a very reliable and consistent load with the 300 gr Bergers. I am confident I can hold 1/2 moa groups at very long distances. That is worth a ton to me.

Thanks!
Jeff

 

[bigngreen]

It sounds like you PPC is a little slow, I run an Axim x51 and I get corrections in seconds, the module takes a few more seconds to open but once it's open I can move through them fast.
It's a lot easier to work out the dope on the desktop then drop it to the PPC!!

 

[bigngreen]

Using your numbers from the last post in Loadbase. With coriolis and MV of 2795. I use a DC of .500 for the G7 and .480 for the G1

G7 419 700yrds = 10.3
995yrds = 19.9
1182yrds = 26.7
1395yrds = 35.9

G1 818 700yrds = 10.4
995yrds = 20.2
1182yrds = 27.2
1395yrds = 36.7

 

[Pdvdh]

Shawn Carlock did some shooting and never complained about the BC for them bullets to be off... you thought they were pretty much on, right?

Eaglet,
I have not shot the .338 Bergers yet. I tested the .308 Berger 210 VLD, 7mm Berger 168 VLD, and 7mm Hornady 162 A-Max. Using Litz's G7 BCs and LB with the DC left at the default value of 0.500, the 1000 yd measured velocities were on the money. One was withing 9 fps of LB3 predicted velocity. One was within ~5 fps of LB3 predicted velocity. And one was within 2 fps of LB3 predicted velocity.

I never mentioned drops because the 1000 yd velocity is a better indication of successful ballistic modeling - IMO. Downrange velocity is relatively unaffected by winds or shooter. But the dope/drops in all three instances were as expected also. I cranked in elevation dope and the bullets hit as predicted as I moved from my 300yd zero height to the ~995 yd targets. Broz is shooting past 1000 yds and I've not chronographed past 1000, but I have confidence that predicted dope and downrange velocity for the three G7 BC bullets I tested would be on-the-money.

But sorry - I have not shot or tested the .338 Berger Hybrid bullets. It would be an interesting exercise due to the current revision of Berger published BC, but I'll wait now until Berger settles on a final bullet design, manufacture, and BC. I've got enough other shooting/testing projects to keep me busy until April 2011, when I'll travel to Kodiak for a brown bear hunt. Our winters are awfully long up here and I tend to complete the long range chronograph work after fall hunting season and before spring bear seasons. Just the way it works best into my schedule - for the time being.

bigngreen,
I use a Dell Axim X51V and I don't have objectionable delay either. On the other hand, I've got nothing to compare speed of operation to, since I've not used Exbal or any other field ballistic software.

 

[Eaglet]

Exbal is much faster at start up Than LB3.0

That's a fact!

Another thing is a fact is that that is at start up where you really feel the difference, after that you don't think about it anymore.

My 22 month old grand son is way faster than me, gets up faster, moves faster etc. etc. But that's the only thing he does better than me!!! ji...ji..ja..ja...
Unfortunately he gets whipped at everything else (for now). That also a fact.

Another thing is you have to keep track of how many programs are running in the back ground of your PDA. The little x on the top right corner does not close the programs it only minimizes them. A person that does not know how to check how many programs are running in the back ground of their PDA is going to experience horrible slow downs...

My Axim has an application called the SwitcherBar, usually it shows on the very top of the main screen; when you click on it it tell you how many programs you're running and how to stop them.

LB3.0 is tremendously powerful and accurate, that comes at a price. You can get real inexpensive Design programs that are lightning fast, that's cool, they won't be good for all your designing, get Roadway Design interfaced with Inroad and man!!!! much, much slower... lots of power and extremely accurate.

Thankfully, It's only at the very start up that LB3.0 can get to 30 to 40 seconds before it gets going; after that it's pretty smooth.

When I'm out in the field the program is the only one running in my pda... I would turn the PDA off leaving the program running in a way that if I need it again I just turn the PDA on and I'm quickly in business.

Broz has a faster processor than mine, his should be running even faster...

 

[Pdvdh]

When I'm out in the field the program is the only one running in my pda... I would turn the PDA off leaving the program running in a way that if I need it again I just turn the PDA on and I'm quickly in business.

Same here Eaglet.

PDA's were a foreign device to me until I purchased the Dell Axim X51V specifically for LB. I still don't know much about the other uses for an X51V. But I did eventually come to learn that after I move into a position and set up to spot/ambush/shoot, I can load a saved Tract, input the existing Field Conditions, Lat, and anticipated azimuth. Then I load the Shoot! or Shoot Solution tab, turn ON spin drift, coriolis, slope, and enter the range to where I expect the game encounter to appear. Then I briefly tap the power button, this seems to place the PDA in hibernation mode with a relatively low battery draw/drain. Tap the power button briefly again whenever I need to get dope for a shot and the unit is quickly up and running just as I last entered data. I can quickly enter any revised pertinent data (wind or temperature changes, azimuth, LRF range), get the corrective dope, and prepare for the shot.

I use desktop and laptop PCs extensively and have for the past ~20 years, but for whatever reason, the PDA involved a bit of a learning curve.

 

[Broz]

after I move into a position and set up to spot/ambush/shoot, I can load a saved Tract, input the existing Field Conditions, Lat, and anticipated azimuth. Then I load the Shoot! or Shoot Solution tab, turn ON spin drift, coriolis, slope, and enter the range to where I expect the game encounter to appear. Then I briefly tap the power button, Tap the power button briefly again whenever I need to get dope for a shot and the unit is quickly up and running just as I last entered data. I can quickly enter any revised pertinent data (wind or temperature changes, azimuth, LRF range), get the corrective dope, and prepare for the shot.

I am aware of this guys. And the above paragraph states my concern well. So now I need a compass and gps to get all the data for a shot?

Here is what I am saying, and I am not bashing LB3.0 I just feel it may not be best for huntig in the field, at least the way I hunt.

Remember I have both on my pda and everything else was wiped off with a hard clean out before either was loaded. This computer is only used for LR shooting / hunting.

I am not doubting LB3.0 is more in depth, and has MORE to look at and refine. But the problem is, it has yet to show me I need it. I guess I am just not sure I need the coriolis, azmuth, Spin drift and all. Look at all the extra steps needed to get a come up elevation. Many more steps mean more places to error.

Bottom line, exbal is now giving me the same or closer dial ups with a whole lot less entries.

Gentlemen, I have applied my self to this 110% with a positive attitude. Further more, I will keep using BOTH.

The next step of this is the fun part. I am preparng to load another 100 rounds. These will be used for cold bore one shots at various targets. I will look at what each program says and see which is closer to a perfect hit.

If it proves that I need to enter a compass reading for azmuth and a gps for latitude to get it right, then I will use LB3.0. But so far I don't see the evidence. The first round hit yesterday at 1395 was done with only a dial up. Windage knob was on zero. Maybe it was luck? But if so I was lucky again today on 4 shots in 3 different directions and distances.

No disrespect ment by my posts. I simply call it like I see it. I know for sure all this has better educated me and for that I THANK YOU ALL!

More practise will tell.

Jeff

 

[Pdvdh]

Hi Jeff,
My post is simply a response to Eaglets point on the PDA operation. I wish I had known that right from the beginning. But now I know.

Don't worry about hurting my feelings with your process, course of action, or preference in ballistic software. I'd guess others feel the same, even though they express a difference of preference. I think you should use whatever software you like the best. Shooting & hunting is supposed to be an enjoyable hobby, so you should run whichever ballistics software that makes your experience most rewarding. Same with chronos versus no chronos. I say live & let live.

Periodically I meet a guy where I shoot that typically comes supplied with 50-100 newly reloaded .308 Win rounds for an afternoon shoot. He doesn't leave till they're all gone. I typically show up with 4 to 12 loaded rounds, set up the chronographs, methodically shoot and collect my data at the 300 yd target - then head home content. The other fellow shoots all 50 - 100 rounds at the 100 yd target in fairly rapid 5-shot groups. Always 5-shot groups. He mentioned he's a Sniper's Hide frequenter. I don't think he really even hunts. If he does, he doesn't mention it. When he's done, he packs up and heads home, seemingly just as content as me. I say good for him. He asks me a few questions every now and then and I likewise express some interest in his latest loads, groups, or whatever. We share some areas of interest and depart on others. He's a pleasant fellow to shoot with.

Anyhow, this example is simply to say - none of us is exactly alike. You shoot a lot more than I do, have better access to wide open countryside to stretch your marksmanship skills, and share those experiences and photos with the rest of us - many of us wishing we had equal ease of good access to such distant targets. I say good for you and good for us. If one method or the another serves your interests better then go with the one that's most rewarding for your own use. This is about you enhancing your hobby, or meeting your personal goals in the most rewarding way.

I wonder how you navigate at the 1000 plus yard ranges without correction for Coriolis and spin drift. As soon as I jumped out to 1000 yds I was befuddled with those two factors. Took a short time to research & educate myself on their affects. First I just cheated my 300 yd zero over to the left ~ 3 1/2 inches so that my 1000yd POIs were good L-R. Then I got LB and now I allow the software to include that correction. I could, and have, dealt with it both ways. But I did have to deal with it one way or another. I would think at your 1300 yd targets that you'd need to make the allowance and you probably do using some method - known or unknown. For example, I know 'jwp475' posts pictures time and again showing his ~1000 +yd targets with the hits dead-centered, and he scoffs at spindrift. Says he makes no allowance for it whatsoever and hits right on L-R wise, from the muzzle out to those distant ranges. I find the difference in experiences interesting. I'm sure he's being affected by it, but some how or another, he's offsetting for it without even knowing it. I'm at 60.4* Lat and that adds a bit more coriolis, but not so much more that coriolis plus spindrift shouldn't still be experienced at 46* Lat in your location, or his. And spindrift is spindrift no matter where one is located on the surface of the earth.

I'm interested on the path you follow to match your field drops, so I'll monitor any posts you offer. Good shooting... gun) gun) seriously! gun) gun)