Calguns.net  

Home My iTrader Join the NRA Donate to CGSSA Sponsors CGN Google Search
CA Semiauto Ban(AW)ID Flowchart CA Handgun Ban ID Flowchart CA Shotgun Ban ID Flowchart
Go Back   Calguns.net > CALIFORNIA SHOOTING CLUBS AND ORGANIZATIONS > California Precision Rifle Club
Register FAQ Members List Calendar Mark Forums Read

California Precision Rifle Club California Precision Rifle Club Forum

Reply
 
Thread Tools Display Modes
  #1  
Old 07-01-2009, 1:03 AM
ar15barrels's Avatar
ar15barrels ar15barrels is offline
I need a LIFE!!
 
Join Date: Jan 2006
Location: Van Nuys
Posts: 40,202
iTrader: 91 / 100%
Default The DOPE on DOPE.

If you are reading this thread, you have probably heard the term DOPE.
It's just another military Acronym for "Data Observed from Prior Engagements".
In the precision rifle world, we might also say it means "Data Obtained from Previous Experience".
Either way, it's information about how your gun/ammo performs in a given set of conditions.

Hard Dope vs. Soft Dope.
There's two kinds of dope, hard and soft.
Hard dope is information YOU gathered in a specific set of conditions.
Soft dope is information simulated by a computer or arrived at by estimating or approximated from other sources of dope.
It's always best to have hard dope for the conditions and location you are shooting in, but it requires shooting a LOT in order to get good dope for every set of conditions in every location.
For most of us, we will work from a combination of hard dope and soft dope with corrections.

Zero you rifle.
Believe it or not, your zero will change with the conditions.
Just because your gun was zeroed perfectly the last time you shot it, don't assume it's still perfectly zeroed when you arrive at a new range with drastically different conditions than when your gun was last zeroed.
When you come out to one of our monthly CaPRC shoots, we start by getting a solid 100yd zero.
This is most important because you are building your dope FROM the 100yd zero.
A 100yd zero range is universal across the USA and almost any range you visit will have a 100yd range available for you to check/adjust your zero.
Once you have a good zero, re-adjust your turrets so they are reading zero.
If you choose not to adjust your zero, you MUST account for any necessary corrections when you start shooting at distance.

Record your Conditions.
Gathering dope without knowing the actual conditions will not help you much.
You need to be observing the barometric pressure and the temperature at the bare minimum.
This usually means purchasing a handheld weather meter.
They are available starting around $100.
If you don't have one, at least track the altitude and temperature.
Then you can go online and find the observed pressure and temperature later to add to your records.
The reason you need to track the pressure and temperature is that these two factors change the density of the air.
The density of the air directly changes how much your bullet drops as it heads towards the target.

Record your come-ups.
You will gather your first hard dope by firing at a target and observing the impact.
Let's say you are shooting federal gold medal match 308 with the 168gr sierra matchking bullet.
http://www.federalpremium.com/produc...le.aspx?id=150
The federal graph shows you drop in inches which is just about worthless, but with some simple math, you figured out that the 26" of drop at 400 equates to about 6.25moa of drop.

So, you dialed 6.25moa on your scope and you fire a round.
The bullet hits the target, but it landed 2" high.
So, you can now observe that 6.25moa was close, but not perfect.
In precision rifle shooting, we want every shot to be perfect so you make a 1/2moa adjustment down for a net 400yd come-up of 5 3/4moa.
Now you fire another round.
This one lands right where you aimed it.
Record that 5 3/4moa as your 400yd come-up for today's conditions.

Continue this process until you have at least 3-4 different distances logged that span the usual distances you expect to be shooting.
Let's say you plan to shoot to 600yds.
You would want to gather hard dope for 300, 400, 500 and 600.
Having perfectly even distances are not important as long as you record WHAT the distance was and WHAT the come-up was for that distance.
At our CaPRC range, you will shoot at 290, 355, 472, 655, 750, 860 and 1000yds.

Check your velocity.
Don't rely on the velocity figures on the end of the ammo box or the reloading manual to actually be true in YOUR rifle.
They may be close, but will rarely be perfect.
Beg, borrow or steal a chronograph and check your ammo in your rifle.
Record this velocity and also note down the temperature at which you fired the test rounds.
It's quite common to see higher velocities on hot days.
We usually have a chrongraph available at CaPRC shoots.
Remember that the bullet comes out of the barrel a couple inches below your line-of sight to be sure you are holding several inches above the chronograph so you don't shoot it!

Working with your dope.
Now that you have a good idea how your bullet performed in the conditions you were shooting, it's time to extrapolate how it would perform in different conditions.
You begin by working with the ballistics program of your choice and entering your bullet, measured velocity and the weather conditions you recorded.
Run a drop card and see what it says.
If you are lucky, the data will match what you recorded by actual firing.
You will rarely be lucky.

Before you can use a ballistics calculator to reliably simulate data in un-tested conditions, you need to fool it to simulate data that matches your hard dope in the same conditions it was gathered.
Using our 400yd example above, you want the program to be telling you 5 3/4moa of drop.
If the computer is telling you something different than what you observed to be true, then you can't trust it.
The trick is to change the BC figure around until you get the computer data (soft dope) to match your hard dope.
Once you arrive at the correct BC to use, record that figure.
You should then be able to use that BC and your measured velocity to make sucessful simulations for other weather conditions and locations.

Creating new Soft Dope.
Let's say it's time to go to a new location for which you have no dope.
Obtain as much information ahead of time as possible as far as what the altitude and weather is like.
Enter this into the ballistics calculator and use your known-good BC and velocity to generate your range card.
Now go shoot at the new location.
As before, record the actual conditions and make notes on your dope card what corrections were necessary.
You will usually be able to see a pattern of corrections on the day of shooting.
For example, the last time I shot at Sacramento, my 500yd dope was about 1/2moa off.
Then my 800yd dope was 1moa off.
I was not suprised at all when I needed to adjust my 1000yd dope by about 2moa.
I even put this correction on the scope before firing my first rounds at 1000yds and it turned out to be correct.

More on pressures.
Within the same weather system, pressure changes dramatically with altitude.
If you only shoot at one location, this won't be as important for you as your dope won't change as much as if you are shooting in different locations with drastically different altitudes.
You should not rely on the barometric pressure you hear on the news as that is corrected for sea level.
For best results, you want to have the ACTUAL barometric pressure where you are shooting.
However, many ballistics programs will allow you to use sea-level-corrected pressure as long as you also input the altitude.
When you have the absolute pressure (also called station pressure), you should not input the altitude into the ballistics software.

My ramblings on Density Altitude.
You may have heard about density altitude being used instead of barometric pressure and temperature.
Density altitude is a single figure that combines station pressure and temperature.
Density Altitude is based on the standard atmosphere model that meteorologists, pilots and ballistic calculators all use.
The standard atmosphere model states that there are standard conditions at different altitudes.



These conditions then corelate with a specific air density.
Therefore, we can also say that there are different air densities at different altitudes.
As we said earlier, air density directly correlates to bullet drop so we are most interested in knowing the air density that we are shooting in.
There's no way to actually measure air density in a handheld device, so we rely on the handheld weather station to calculate density from the pressure, temperature and humidity that can actually be measured.
The density is expressed as a density altitude.

Let's say you turn on your kestrel and it tells you that the density altitude is 1900ft.
What that means is that the air you are standing in right now (regardless of your actual altitude) has the same density as if you were at 1900 feet in the standard atmosphere model.

Density altitude is a very convienent way to log your weather conditions because it boils everything down to one figure.
You can even go so far as to generate a set of dope cards based only on density altitude.
Once you make, test and correct these cards, you can arrive at any location, turn on your kestrel and select the dope card that is appropriate for the moment.
Something else to note is that the conditions change throughout the day.
I usually see a 1000-2000ft density altitude change from morning to afternoon.
In my 308 data, I see that each 1000ft of density altitude change accounts for about 1moa of elevation adjustment at 1000yds.
What this means is that you really need to stay on top of the weather conditions and be using the correct dope for the MOMENT, not just the day.
__________________
Randall Rausch

AR work: www.ar15barrels.com
Bolt actions: www.700barrels.com
Foreign Semi Autos: www.akbarrels.com
Glock, XD and M&P pistols, Benelli and Remington shotguns: barrel, sight, trigger and receiver work.
Most work performed while-you-wait, evening and weekend appointments available.
Founding member of the CAPRC

Last edited by ar15barrels; 04-06-2010 at 11:12 PM..
Reply With Quote
  #2  
Old 07-01-2009, 7:29 AM
DirtRacer151's Avatar
DirtRacer151 DirtRacer151 is offline
Senior Member
 
Join Date: Oct 2008
Location: Riverside, CA
Posts: 2,353
iTrader: 30 / 100%
Default

ahhhh just what i needed!! Thanks Randall.. i have some studying to do after work
Reply With Quote
  #3  
Old 07-01-2009, 7:43 AM
rksimple's Avatar
rksimple rksimple is offline
Calguns Addict
 
Join Date: Jan 2006
Location: T-Town
Posts: 6,218
iTrader: 11 / 100%
Default

This is good info, and a topic that seems to come up somewhat frequently. Playing with online ballistics calculators by inputting hard data is a good way to predict future dope in other loactions and conditions. Don't rely merely on close range data either. Use a few points to get information. Use a couple close in and maybe a couple far away. Like 400, 650, and then 850 and 1k, or somewhere in between. You may have to tweak MV, BC, etc.

For those with PDA's, I highly recommend Field Firing Solutions:

http://www.precisionworkbench.com/

It has a function to do exactly what was talked about. It will automatically find the true BC of the bullet and use that info to predict bullet behavior in other conditions. Great software.
__________________
GAP Team Shooter 5

Last edited by rksimple; 07-01-2009 at 7:46 AM..
Reply With Quote
  #4  
Old 07-01-2009, 7:57 AM
Vu 308's Avatar
Vu 308 Vu 308 is offline
Senior Member
 
Join Date: Oct 2007
Location: Nor Cal
Posts: 2,380
iTrader: 12 / 100%
Default

+1 for Blaine Field's software.

It is the best software I've seen used on our range to make good solid hits out to 1K relying strictly on computer generated data.

Vu
__________________


Please visit us @ www.ncpprc.com for more info.
Reply With Quote
  #5  
Old 07-01-2009, 8:11 AM
Teletiger7's Avatar
Teletiger7 Teletiger7 is offline
Veteran Member
 
Join Date: Oct 2005
Location: San Fernando & Santa Clarita Valleys
Posts: 2,727
iTrader: 47 / 100%
Default

I think many will find this thread helpful. Especially the stuff on density altitude. Can this be a sticky?

Last edited by Teletiger7; 07-01-2009 at 8:17 AM..
Reply With Quote
  #6  
Old 07-01-2009, 8:18 AM
rksimple's Avatar
rksimple rksimple is offline
Calguns Addict
 
Join Date: Jan 2006
Location: T-Town
Posts: 6,218
iTrader: 11 / 100%
Default

Stuck.
__________________
GAP Team Shooter 5
Reply With Quote
  #7  
Old 07-01-2009, 9:28 AM
StraightShooter's Avatar
StraightShooter StraightShooter is offline
Senior Member
 
Join Date: Jun 2007
Location: Royse City, Texas
Posts: 2,168
iTrader: 22 / 100%
Default

In addition, it is a good idea to get a set of sheets/cards that tell you your hold offs in different wind conditions. You can use the free JBM software on the net to generate cards for different wind conditions based on the velocity and BC of the bullet you are using. I have cards in 2 mph increments from 2-15 mph and they have been very accurate.
__________________

Brandon M.
Reply With Quote
  #8  
Old 07-01-2009, 9:54 AM
Novadesigns's Avatar
Novadesigns Novadesigns is offline
Senior Member
 
Join Date: May 2007
Location: Glendale, CA
Posts: 1,182
iTrader: 2 / 100%
Default

YAY! Nice and concise Randall. Thank you.
__________________
NRA
IDPA
USPSA
Reply With Quote
  #9  
Old 07-01-2009, 10:05 AM
Teletiger7's Avatar
Teletiger7 Teletiger7 is offline
Veteran Member
 
Join Date: Oct 2005
Location: San Fernando & Santa Clarita Valleys
Posts: 2,727
iTrader: 47 / 100%
Default

For anyone who doesn't already have it, here's the JBM small arms ballistics link:

http://www.eskimo.com/~jbm/calculati...culations.html
Reply With Quote
  #10  
Old 07-01-2009, 10:46 AM
Gnzrme Gnzrme is offline
Senior Member
 
Join Date: Oct 2007
Location: Canyon Country, CA
Posts: 755
iTrader: 2 / 100%
Default

Yeehow!!! Now I have something to work on...excellent work Randall and just what us noob's need....
Reply With Quote
  #11  
Old 07-02-2009, 11:37 PM
Bserebreni Bserebreni is offline
Senior Member
 
Join Date: Jan 2009
Location: Sherman Oaks
Posts: 619
iTrader: 8 / 100%
Default Dope

Hi Randall and guys: This was great. I went shooting today with Stephen and we use my 308 and I used at the last shoot. At Angeles I seem to do better......no pressure, but I'll get there. Stephen did the shooting and I spotted. We went to 600. The dope on my iphone Ballistics was office considerable. So, we walked it a good shot.I'm using 70/NF and it's only about 150 rounds. Theres lots of work to do. Now getting to the post YOUR dope on dope was great. I'll go out on saturday and follow your advice. Again, thanks for being so giving.
Ben
Reply With Quote
  #12  
Old 10-26-2009, 12:37 AM
Gnzrme Gnzrme is offline
Senior Member
 
Join Date: Oct 2007
Location: Canyon Country, CA
Posts: 755
iTrader: 2 / 100%
Default

Ok, I am playing with a balistics program (Precision Shooters Workbench). What data should I manipulate to get this soft data to match my hard data: BC, velocity, atomospheric data.....?
__________________
Steven P. Rogers, RN CEN

I must go...I must smell that smell...The smell of burnt gunpowder blowing down the line, the sweet sound of lead connecting with metal...I have to have it and hear it....I know you know what I mean, I know Bob would know what I mean.... Its nothing that a little steri strips and some tegaderm won't fix...

Broke into the wrong Goddammed rec room didn't you you bastard!!!
Burt Gummer for President 2012
Reply With Quote
  #13  
Old 10-26-2009, 7:43 AM
ar15barrels's Avatar
ar15barrels ar15barrels is offline
I need a LIFE!!
 
Join Date: Jan 2006
Location: Van Nuys
Posts: 40,202
iTrader: 91 / 100%
Default

Quote:
Originally Posted by Gnzrme View Post
Ok, I am playing with a balistics program (Precision Shooters Workbench). What data should I manipulate to get this soft data to match my hard data: BC, velocity, atomospheric data.....?
bc.

On the atmospheric data, assume that the temperature was 2-3 degrees warmer for each distance we shot at.
You won't be able to use the same atmospherics for all your dope because it changed throughout the day.
__________________
Randall Rausch

AR work: www.ar15barrels.com
Bolt actions: www.700barrels.com
Foreign Semi Autos: www.akbarrels.com
Glock, XD and M&P pistols, Benelli and Remington shotguns: barrel, sight, trigger and receiver work.
Most work performed while-you-wait, evening and weekend appointments available.
Founding member of the CAPRC
Reply With Quote
  #14  
Old 12-28-2009, 7:01 PM
DirtRacer151's Avatar
DirtRacer151 DirtRacer151 is offline
Senior Member
 
Join Date: Oct 2008
Location: Riverside, CA
Posts: 2,353
iTrader: 30 / 100%
Default

Randall, Im playing with my new Kestrel and trying to figure out exactly what i need to do on JBM to get accurate soft dope. Now that i can get my own DA measurements i'm ready to start keeping better track of the conditions. Im getting a little confused by JBM though.

-I thought i was supposed to zero out temp, hum, and pressure then input the DA into the Altitude box and check the box that says standard atmosphere at altitude is that correct? But when i zero the pressure box it throws back a input error??

-Does the pressure corrected box need to be checked?

Also what BC are you using for 22lr? I have been using .135 but my actual drop is more then what JBM is telling me its supposed to be by .3mils at 200yds

Last edited by DirtRacer151; 12-28-2009 at 7:05 PM..
Reply With Quote
  #15  
Old 12-28-2009, 11:09 PM
ar15barrels's Avatar
ar15barrels ar15barrels is offline
I need a LIFE!!
 
Join Date: Jan 2006
Location: Van Nuys
Posts: 40,202
iTrader: 91 / 100%
Default

Quote:
Originally Posted by DirtRacer151 View Post
Randall, Im playing with my new Kestrel and trying to figure out exactly what i need to do on JBM to get accurate soft dope. Now that i can get my own DA measurements i'm ready to start keeping better track of the conditions. Im getting a little confused by JBM though.

-I thought i was supposed to zero out temp, hum, and pressure then input the DA into the Altitude box and check the box that says standard atmosphere at altitude is that correct? But when i zero the pressure box it throws back a input error??

-Does the pressure corrected box need to be checked?

Also what BC are you using for 22lr? I have been using .135 but my actual drop is more then what JBM is telling me its supposed to be by .3mils at 200yds
Which JBM calc are you using?
I use micro cards and you just input the density altitude AS the altitude.
If the read the comments, he tells you that he is only calculating the air density from the density altitude figure.
The temperature and velocity figures you input are only used to figure velocity at different temperatures.
__________________
Randall Rausch

AR work: www.ar15barrels.com
Bolt actions: www.700barrels.com
Foreign Semi Autos: www.akbarrels.com
Glock, XD and M&P pistols, Benelli and Remington shotguns: barrel, sight, trigger and receiver work.
Most work performed while-you-wait, evening and weekend appointments available.
Founding member of the CAPRC
Reply With Quote
  #16  
Old 12-28-2009, 11:59 PM
DirtRacer151's Avatar
DirtRacer151 DirtRacer151 is offline
Senior Member
 
Join Date: Oct 2008
Location: Riverside, CA
Posts: 2,353
iTrader: 30 / 100%
Default

Your saying you use this calculator?
http://www.jbmballistics.com/cgi-bin/jbmucard-5.0.cgi

Running my numbers on it they are much closer then this one that i was using earlier. Whats the difference?
http://www.jbmballistics.com/cgi-bin...j_simp-5.0.cgi
Reply With Quote
  #17  
Old 12-29-2009, 12:06 AM
ar15barrels's Avatar
ar15barrels ar15barrels is offline
I need a LIFE!!
 
Join Date: Jan 2006
Location: Van Nuys
Posts: 40,202
iTrader: 91 / 100%
Default

Quote:
Originally Posted by DirtRacer151 View Post
Your saying you use this calculator?
http://www.jbmballistics.com/cgi-bin/jbmucard-5.0.cgi
That's the one I use.
I don't know the differnces in all the cards, but that one works good for me.
__________________
Randall Rausch

AR work: www.ar15barrels.com
Bolt actions: www.700barrels.com
Foreign Semi Autos: www.akbarrels.com
Glock, XD and M&P pistols, Benelli and Remington shotguns: barrel, sight, trigger and receiver work.
Most work performed while-you-wait, evening and weekend appointments available.
Founding member of the CAPRC
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT -8. The time now is 5:11 PM.




Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Proudly hosted by GeoVario the Premier 2A host.
Calguns.net, the 'Calguns' name and all associated variants and logos are ® Trademark and © Copyright 2002-2016, Calguns.net an Incorporated Company All Rights Reserved.