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LoadBase 3.0 Mobile w/G7 BC Test Results

 
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  #1  
Old 09-19-2009, 03:54 AM
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LoadBase 3.0 Mobile w/G7 BC Test Results

Patagonia LoadBase 3.0 Mobile ballistic software users may find this post intriguing. I've been using LoadBase 2.0 Mobile, the upgraded LoadBase 3.0 Mobile, and now the recently updated LoadBase 3.0 with the added ability to input G7 ballistic coefficients. LoadBase 3.0 Mobile only accepted G1 BCs until this recent update.

With LoadBase 2.0 Mobile and the initial version of Loadbase 3.0 Mobile (G1 BCs), I had already been shooting Berger VLDs in my 300 Win Mag (210 VLD) and 7mm Rem Mag (168 VLD) . I had already recorded velocities with the 210 & 168 VLDs at the muzzle, 290 yds, and 987 yds over a dual chronograph setup, which helps to confirm I'm getting credible chrono readings. With these velocities, I used the Drag Coefficient (DC) tab in the Analyzer Module to develop a G1 BC and a DC for both bullets.

With these BC and DC values input into LB Mobile, I field tested the LoadBase predicted drops at 295, 600, and 987 yds with both bullets. The 210VLD POIs from my 300 Win Mag were dead nuts on with the LoadBase predicted drops. The 168VLD POIs were a pretty good match, however I did tweek the DC value with the 168VLDs in order to improve the predicted drops closer to my measured drops.

After Bryan Litz announced he was coming out with G7 BCs for the Berger bullets, and after I learned LoadBase 3.0 would be updated to allow use of G7 BCs, I was looking forward to using Bryan's G7 BCs with LoadBase 3.0. I was thinking this combination might result in very good correlation of predicted drops to field tested POIs.

Since I already had the field drops (POIs) and chrono'd velocities out to 987yds for both bullets, after Gus released his G7 BC LB3.0M update, all I needed was some time to input the Berger G7 BCs for both bullets into LB3.0M to learn how close the predicted drops and velocities matched my actual field drops and velocities.

Well I finally made time and here are some G7 BC LB3.0 Mobile results:

168 VLD. . . LB3.0 G7 BC (DC=0.5) Predicted . . . . Chronographed Velocity . . . . Difference
290yds . . . .2621 fps . . . . . . . . . . . . . . . . . . . .2632 fps . . . . . . . . . . . . . . 11 fps
987yds . . . .1643 fps . . . . . . . . . . . . . . . . . . . .1673 fps . . . . . . . . . . . . . . 30 fps
168 VLD. . . LB3.0 G7 BC (DC=0.5) Predicted . . . . Measured Drop . . . . . . . . . . Difference
987yds . . . .-195.1" . . . . . . . . . . . . . . . . . . . . .-190.9". . . . . . . . . . . . . . .. 4.2"

210 VLD. . . LB3.0 G7 BC (DC=0.5) Predicted . . . . Chronographed Velocity . . . . Difference
290yds . . . .2546 fps . . . . . . . . . . . . . . . . . . . .2546 fps . . . . . . . . . . . . . . 0 fps
987yds . . . .1553 fps . . . . . . . . . . . . . . . . . . . .1584 fps . . . . . . . . . . . . . . 31 fps
210 VLD. . . LB3.0 G7 BC (DC=0.5) Predicted . . . . Measured Drop . . . . . . . . . . Difference
987yds . . . .-211.4" . . . . . . . . . . . . . . . . . . . . .-207.1". . . . . . . . . . . . . . .. 4.3"

I used the default DC of 0.5 with the Berger G7 BCs. LB3.0 Mobile / Berger G7 BC predicted velocities at 987yds were ~30 fps slower than my chronographed velocities with both bullets. The predicted drops at 987yds were ~4 1/4" greater than my measured drops with both bullets. The predicted 987yd velocities are ~1.9% less than my chronographed velocities. The predicted 987yd drops are ~2.1% greater than my measured drops.

My opinion? I'm pretty pleased with these LB3.0M G7 predicted values.

Last edited by phorwath; 09-19-2009 at 05:17 PM.
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  #2  
Old 09-19-2009, 04:39 AM
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Re: LoadBase 3.0 Mobile w/G7 BC Test Results

Phorwath,

Thank you for sharing. It's very interesting!
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HEBREWS 13:8
Jesus Christ the same yesterday, and to day, and for ever.

Our Lord Jesus said that as it was in the days of Noah and
also as it was in the days of Lot so it shall be in the days...
It's happening again!!! God sent to us His prophet, and His Word
to this generation and we once more are rejecting it as was prophesied!!!

---> As promised, God Sent His Prophet to us!
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  #3  
Old 09-19-2009, 08:30 AM
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Re: LoadBase 3.0 Mobile w/G7 BC Test Results

Phorwath,
Thanks for posting this. That is a pretty good match.
I'm curious about a couple things;
1) Your chronograph set up that lets you measure velocity that far downrange.
2) How does JBM compare to your measured data (using G7's)?

It's great that we have a mobile option for G7 BCs now.

Take care,
-Bryan
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  #4  
Old 09-19-2009, 02:16 PM
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Re: LoadBase 3.0 Mobile w/G7 BC Test Results

Quote:
Originally Posted by bsl135 View Post
Phorwath,
Thanks for posting this. That is a pretty good match.
I'm curious about a couple things;
1) Your chronograph set up that lets you measure velocity that far downrange.
2) How does JBM compare to your measured data (using G7's)?

It's great that we have a mobile option for G7 BCs now.

Take care,
-Bryan
Bryan,

Yes, considering all the potential background errors and noise a person can add to the data collection process, I thought those results were certainly within the margin of error. I'm sure I could tweek the drag coefficient in LB3.0 Mobile for a very close fit to my measured data, but I just wanted to test the software with the G7 BCs and the default drag coefficient value of 0.5

1) I run both an Oehler 33 and a PACT PC2 in series with the skyscreens mounted on a single rail using a 6 foot spacing and 4.5 foot spacing, respectively. This way if the difference between the two recorded velocities is out of whack, I have a way of knowing that either one, or both, of the chronographs spit out an erroneous value and I can discount or completely disregard the data. I don't worry about getting the same velocity from each chrono. I only worry about the magnitude of the difference between the two values on a shot to shot basis. For example, on a good data set when the equipment doesn't give me any hiccups, the actual difference between the two chrono readings (with one brand, style, caliber, and weight of bullet) over a string of shots might vary between 17 to 22 fps. Sometimes I've had 6 or 7 shots where the difference in velocity over all of the shots will only vary by a maximum of 3 fps for any single shot. Then I'm feeling pretty darn good about the quality of the collected data... If I get a data set for a shot such that the difference between the recorded velocities is 30-55 fps, or 0-10 fps (when the average difference should be 17-22 fps) then I know I've recorded a bogus value from one or both chronographs and I can disregard, or at least qualify, those values. Having two chronographs recording each and every shot is quite an eye opener in itself. It causes me to smile anytime I'm engaged in a conversation with another shooter who's scratching his head trying to interpret chrono data from a single chrono. In my experience, I would no longer even think of getting serious about the collection of, and reliance on, chrono data for purposes of load development without a dual chrono setup to provide this type of confirmation that the data are trustworthy.

As far as how do I chrono at 987 yds? It takes nerves of steel if you haven't fabricated some kind of protective device to protect your sky screens. And I didn't. It's not something I do on a regular basis - my nerves can't handle it! I'm trying to figure out what type of a skyscreen protector I might be able to construct. Something shy of parking a bulldozer blade in front of my skyscreens. In addition, it involves a lot of back-and-forth driving, because I have to drive down to the target / chrono's after each and every shot in order to confirm whether or not the shot was placed good enough to collect velocities. Alaska is 4-Wheel Drive country and I start out will a full tank of gas.

2) I haven't run this comparison with JBM and the G7 BCs. Hadn't even thought about it, but I may do that as a point of curiousity. I was eager to run the LoadBase predicted values because LB3.0 Mobile is what I have in my toolbox when I'm hunting. If I run JBM G7 data I'll post those results also.

Last edited by phorwath; 09-19-2009 at 05:24 PM.
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  #5  
Old 01-14-2010, 08:23 PM
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Re: LoadBase 3.0 Mobile w/G7 BC Test Results

Phorwath,

I was just re-reading your thread and... man I've got to tell you, you really got
nerves of steel to shoot through your chronos at 987 yards with no protection.
I just don't think my rifle, or my ammo nor me are good enough to do the same. I do have tow chronograps and plan on having them for a long time.
That's great work, awesome shooting.
Thanks again for taking the time to share that.
__________________
-----------------------------

-----------------------------
HEBREWS 13:8
Jesus Christ the same yesterday, and to day, and for ever.

Our Lord Jesus said that as it was in the days of Noah and
also as it was in the days of Lot so it shall be in the days...
It's happening again!!! God sent to us His prophet, and His Word
to this generation and we once more are rejecting it as was prophesied!!!

---> As promised, God Sent His Prophet to us!

Last edited by Eaglet; 01-16-2010 at 11:07 PM.
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  #6  
Old 01-14-2010, 09:13 PM
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Re: LoadBase 3.0 Mobile w/G7 BC Test Results

Buddy, you've been busy!! I also concur your crazy for shooting through your chronograph at 987 too!! However I do thank you for doing it! Great post!!
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  #7  
Old 01-16-2010, 10:35 PM
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Location: Alaska
Posts: 3,417
Re: Pics of Skyscreen Protector

Next time I shoot at 1000 yds my skyscreens will be protected from bullet damage by this protective stand I constructed last month. 12" diameter, 1/2" thick AR 500 steel plate on an adjustable-height stand. The stand is welded to a piece of railroad tie for stability and support on the ground. Two pieces of square channel steel which tube within each other, comprise the adjustable stand. AR 500 steel plate is adjusted to height required to protect the skyscreens. The idea is to shoot just over the top the AR 500 plate which will run the bullet right over the dual sets of skyscreens. If a bullet comes in at skyscreen height it will be blocked by the AR 500 plate. This way I won't need the rubber underpants while squeezing off the trigger.

Here's a few pics:

First the protective AR 500 steel plating spraypainted white.


Next the adjustable stand showing cross pin and holes drilled every 1 3/4" to select proper height.


Lastly, the piece of railroad tie supportive base I decided to use. The sliding adjustable steel post separates from the AR 500 plate and the railroad tie for purposes of transport.


At 1000yds, I believe the 1/2" thick AR 500 plate will stop any bullet I plan to shoot out of any of my rifles. Max will be 300 SMK from a 338 Edge -> 1000 yds.
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