Range Report G1 or G7

[ghorsley]

When using my iPhone ballistics app selecting G1 gives me a 14.68 come up.
When selecting G7 I get 11.95 come up.
My actual range data is much closer across the board selecting G1.

In looking up the differences, using my bullet, 175 Sierra HP Match King, I should be selecting G7.
If I do this all my dope is way off.

What's up with this? Thanks, Gil Horsley

IN ANSWERING PLEASE TRY AND KEEP IT SIMPLE.....I HATE MATH.

 

[damoncali]

Every bullet has a drag function that will give the best results. For almost all long range bullets, including the 175MK, the better choice is the G7. When you use the G7 drag function, you must use a G7 BC. (a G7 BC is a different number than a G1 BC). It's hard to say what's going wrong without more detail.

 

[usafabrad]

Make sure you arent just arbitrarily changing the G1 to G7 option without changing the BC to the G7 BC. A 175 SMK has a G1 BC of around .5, which falls off to the high .4's as velocity drops. The same bullet's G7 BC is about .243. Make sure you have the right BC matched up with the right drag model or the whole thing will be wonky.

G7 model more closely resembles the drag curve of a modern secant ogive/ boat tail bullt like the 175MK.

 

[Rob01]

Exactly. Don't just change G1 to G7 and not change the actual number. A good G1 for that bullet is .496. it's .505 over 2800fps but most .308s won't get it going that fast.

I have always used G1 BCs and continue to with all my AMAX bullets and other HPBT bullets. Always worked great. The G7 has become popular in recent years but the G1 works as well.

 

[damoncali]

I suppose that it's worth noting that for that bullet at normal velocities and ranges, the difference between G1 and G7 is slight. It will start to show up a longer ranges - past 600 yards.

 

[bodywerks]

I suppose that it's worth noting that for that bullet at normal velocities and ranges, the difference between G1 and G7 is slight. It will start to show up a longer ranges - past 600 yards.

This.
For boat tail rifle bullets use the g7 whenever possible. I suspect you assigned a g1 bc to a g7 standard.
In shooter, i show a g1 BC of .475 and a g7 BC of .243. If you apply . 475 to the g7 standard you get the results you posted.

 

[Rob01]

I have used G1 with a 210 VLD out to 1650 yards with my 300WM and it tracked right on. Don't assume G1 won't work at longer ranges. It works just fine out past 600 yards. It's what I always use to shoot matches to 1000+.

 

[Aimsmall55]

I have used G1 with a 210 VLD out to 1650 yards with my 300WM and it tracked right on. Don't assume G1 won't work at longer ranges. It works just fine out past 600 yards. It's what I always use to shoot matches to 1000+.

I too use the g1 on basically everything I shoot. At 1202 yards I was shooting 208 amaxs with .648 and it was spot on. Everything I've shot 1000+ has been with the G1 and if you know your muzzle velocity , scope height , and have a load that yields a very low sd , your in business. That is with quality equipment. Including Remington 700's.

 

[Graham]

I have used G1 with a 210 VLD out to 1650 yards with my 300WM and it tracked right on. Don't assume G1 won't work at longer ranges. It works just fine out past 600 yards. It's what I always use to shoot matches to 1000+.

I agree. I still use G1, even for ELR (with FFS with a single G1 value), I simply calibrate my ballistics program.

 

[Rthur]

At Rifles Only a few years ago Frank helped me fine tune my ballistic app. This one was Bullet Flight. It seemed to like using the g1 more than the g7. I would say that some apps prefer the g1 and some the g7. I haven't used them all but this has been my experience.

R

 

[demolitionman]

Help. Define MV and SD when you guys abbreviate with those letters....

 

[bodywerks]

MV= muzzle velocity
SD= standard deviation

 

[MALLARD]

you should really generate your own BC's instead of using the ones provided. If you do that it wont really matter if you use th G1 or G7 since you'll be getting very similar outputs.

 

[Rob01]

If you are using dialed on scope data to tune a BC you better make damn sure that scope tracks 100% as if not you are using bad data to determine a BC, which you actually aren't doing but tailoring the round to your specific set up.

 

[jbailey]

Most guys can't shoot the difference between G7 and G1. Variations in MV and/or environmentals will overwhelm the difference for most. Use either one with confidence to a long long range. If you are going 2000+yds, maybe start to worry about G7. Just make sure you are entering G1 BCs when you input into a G1 model and G7 BCs when you input into a G7 model. I'm sure the OP put his G1 into a G7 model.

 

[Graham]

Most guys can't shoot the difference between G7 and G1.

What is the difference? It's simply a different way of stating the same thing. I can't hold the difference between two inches and 5.08 centimeters either.

 

[damoncali]

What is the difference? It's simply a different way of stating the same thing. I can't hold the difference between two inches and 5.08 centimeters either.

It is not the same thing. They are different approximations of the bullets actual drag. One of the two will be a better fit (more accurate). Usually, that will be the g7. The difference between the two calculated trajectories will be small- almost zero until you are out at 600-1000 yards, and dependent on the bullet. But if you are using a g1 on a bullet that should use a g7, you are introducing an error, however slight. At very long ranges, it's not insignificant, as the difference widens near the sound barrier.

 

[Graham]

It is not the same thing. They are different approximations of the bullets actual drag. One of the two will be a better fit (more accurate). Usually, that will be the g7. The difference between the two calculated trajectories will be small- almost zero until you are out at 600-1000 yards, and dependent on the bullet. But if you are using a g1 on a bullet that should use a g7, you are introducing an error, however slight. At very long ranges, it's not insignificant, as the difference widens near the sound barrier.

Which bullets 'use' a G7 and which bullets 'use' a G1?

 

[Captain Kirk]

I have found that I have needed to modify my BC to get my DOPE to line up, this has been the case with most bullets. I tried playing with velocity which is a band-aid at a specific distance, so I took my velocity matched with my impacts, noting the discrepancies in my ballistic program. After all that data was there, I tweaked the BC until ALL the numbers lined up. I had major issues in my data before but have been able to get 1st round hits a little past 1100 yards to date, using a "modified" G1. Don't trust your chronograph, and don't believe every posted BC as gospel.

Kirk R

 

[Lowlight]

It is not the same thing. They are different approximations of the bullets actual drag. One of the two will be a better fit (more accurate). Usually, that will be the g7. The difference between the two calculated trajectories will be small- almost zero until you are out at 600-1000 yards, and dependent on the bullet. But if you are using a g1 on a bullet that should use a g7, you are introducing an error, however slight. At very long ranges, it's not insignificant, as the difference widens near the sound barrier.

That is barely true on a good day...

For 40 years we used G1 with no ill effects, the "slight error" you are talking about is a function of Point Mass as a ballistic solver... "it" is more concerned with the G function, the bullet doesn't care at all.

The best software on the market does not use "point mass" and does not care, so you have programs like Field Firing Solutions which is accurate beyond 2000m plus... that doesn't even let you use G7 it only uses G1... go figure G1 Ballistics that work beyond 1000 yards.

There is more than one ballistic method and model out there, just because one favors G7 doesn't make it the end all, and in fact you can still get great dope with G1 using a Point Mass Solver. Try banding G1 and see how good it is...

Also not all bullets have a G7 number so what happens if you pick a bullet that only has a G1 value, does it fall out of the sky in horror ?

 

[Captain Kirk]

Next ask Frank if you should select "spin drift" on your program....

 

[damoncali]

Which bullets 'use' a G7 and which bullets 'use' a G1?

Almost all modern sporting bullets are better described by a G7 drag function than a G1 drag function.

 

[damoncali]

That is barely true on a good day...

For 40 years we used G1 with no ill effects, the "slight error" you are talking about is a function of Point Mass as a ballistic solver... "it" is more concerned with the G function, the bullet doesn't care at all.

The best software on the market does not use "point mass" and does not care, so you have programs like Field Firing Solutions which is accurate beyond 2000m plus... that doesn't even let you use G7 it only uses G1... go figure G1 Ballistics that work beyond 1000 yards.

There is more than one ballistic method and model out there, just because one favors G7 doesn't make it the end all, and in fact you can still get great dope with G1 using a Point Mass Solver. Try banding G1 and see how good it is...

Also not all bullets have a G7 number so what happens if you pick a bullet that only has a G1 value, does it fall out of the sky in horror ?

Educate me. I fail to see what I said that is not true. Every bullet can be described by any drag function you like. Some will do it better than others - you could use a sphere if you like, but you'll get bad results. That's just observation, and is independent of the method used to calculate a trajectory. The difference between a G7 and a G1 is very small for regular bullets at regular velocity at regular range. I don't see that as terribly controversial.

 

[Lowlight]

Pesja' based solutions are not G Dependent ... it likes to use G1.

Patagonia Coldbore and Lex Talus FFS are based on his work.

Here is my favorite chart to contradict the hype...

The numbers are so close it doesn't matter once you step away from Point Mass... Doppler w/ G1 vs G7

What is NOT TRUE is that G1 fails after 600 -1000 yards... completely false.

 

[Graham]

Almost all modern sporting bullets are better described by a G7 drag function than a G1 drag function.

That's not what you said before. Now you are avoiding the question.

 

[TiroFijo]

Even with a normal program like the JBM, carefully selecting the G1 BC you can usually get 0.2-0.3 MOA max difference with a humble 308 in trajectory between G1 and G7 up to 1000 yds... that's about 2-3" at this distance, so it is not a really big deal considering that there are other more important variables at play. If you use several "stepped" G1 values (like the ones availabe from Sierra) you can get as good as it gets.

Remember that the accuracy of the program is only part of the problem, you have to accurately imput the environmental variables (including perhap vertical wind components that affect POI), muzzle velocity (that normally varies with temperature), make sure the clicks in the scope match the setting to get the proper elevation at several ranges, etc. It is very tricky to get an exact a match between the program and observed POI, and you may have to tweak things a little.

 

[damoncali]

I'm not trying to argue. I think you guys are reading something that I'm not trying to write. Perhaps you could phrase your question more directly?

Let me attempt to clarify what I meant:

First, this is all well into the territory of nitpicking and edge cases. Perhaps I didn't make that clear enough.

A drag function is nothing more than a curve that matches up drag coefficient and speed. Every bullet has a drag function, but they are painful to measure. So we use standard functions as approximations. G1 and G7 are two of them. They are different. Therefore, a bullet's actual drag function will match up with one of them better than the other and provide better results with that drag function. For almost all long range sporting bullets, the better fit is with the G7 drag function. The differences tend to be at low velocity. It's not like picking MOA or mils, which are truly equivalent and a matter of preference.

Nobody is suggesting that a G1 will "fail" at all. I've used them successfully for many years with useful results to even think that. With *some* bullets you will start to see a divergence in the predicted trajectories between G1 and G7 as early as 600 yards that will eventually amount to a few clicks. For others the difference is so slight as to not matter at all, as Lowlight's chart shows.

Many will say "well who cares then?" and that's a totally legitimate point if your goal is to hit the target with the equipment available. But to me it's interesting because the concepts can lead to useful improvements over time.

 

[Greg Langelius *]

These differences will become accentuated at extreme (near sonic transition) ranges. This has always proved to be a critical factor when shooting the .308 at around 1Kyd, and is the main reason why I no longer own any .308's, replacing the with .260's and 280's.

I have always used G1, and concurrently experienced observed POI deviations from computed POI predictions.

As noted by previous posters, the difference is tolerably minor. It almost, but not quite, disappears in the 'background noise' of environmental variables which defy computation.

These vary from shooting session to shooting session anyway; so I have concluded that calculation simply cannot be depended upon to render (for me, anyway) an absolute and perfect POI prediction, but should simply serve as a means to 'get on paper'.

I have always suspected that Mother Nature looks on LR Precision Rifle shooters while wearing a wicked grin. Sometimes I think of her in her alternate persona; as 'Mother Murphy". I remain an avid disciple of Mother Murphy.

...and Mother Murphy rides again...

Greg

 

[Lowlight]

There are too many variations to 'predict" the computer can only do so much.

Also the shooter is a huge variable as we all don't release the shot the same. That leads to deviations beyond what the computer can calculate.

Some variables include actual barrel twist, (how many measure it and input into the computer) powder variations, bullet weight variations, as noted, scope click values and accuracy. Combine with things like the environmental conditions, and lastly actual winds the bullets encounters on its flight and there is a lot missing from the model.

This is why we recommend you shoot and record your actual dope. Ballistic programs are a starting point and not necessarily the end all. They can help predict the changes when things change, or they can help fine tune the dope on an UKD Target, but mostly they are just a guide towards the target. Lucky for us, we have targets big enough to take up the slack. Still they are getting better and do well to distance when properly calibrated to both the shooter and his equipment. This calibration is not always as simple as shooting and see how it lines up, but fine tuning it over a period of days under as many different conditions as possible. The results must be recorded and then worked on to line the computer up with the shooter.

Garbage in yields Garbage out and unfortunately we can fall into that garbage category if we are not consistent in our release.

In the past 1 MOA was more than acceptable, today it is closer to 1/2 MOA everyone strives for when it comes to a computer. Lastly, the expectations can be a little high if you believe you can just throw some numbers in blind and it will all be good. The market for software boast some pretty incredible claims that are rarely qualified.

 

[mudpig]

A very good read on the subject is Bryan Litz's book: Applied Ballistics.....

AB for Long Range Shooting

In a very down to earth fashion, he explains the G1/G7 difference and even gives TESTED G values. Goes thru the use of ballistic programs and even supplies a Ballistic Program with his book. He goes into the importance of verifying that your scope is level and the ACTUAL click values of your scope (not advertised). It's a very good read!!!

Chris

 

[bodywerks]

A very good read on the subject is Bryan Litz's book: Applied Ballistics.....

AB for Long Range Shooting

In a very down to earth fashion, he explains the G1/G7 difference and even gives TESTED G values. Goes thru the use of ballistic programs and even supplies a Ballistic Program with his book. He goes into the importance of verifying that your scope is level and the ACTUAL click values of your scope (not advertised). It's a very good read!!!

Chris

It is a good book. In theory, the g7 is a better way to go imo, but like others have said, there are so many other variables that many shooters never take into consideration that will affect POI far more than BC error (actual twist rate verses advertised, actual click value of the scope, actual mv for the fired shot, scope cant, variations in bullet shape/weight/ogive from lot of a given bullet, actual distance to target verses calculated distance, actual density altitude...the list goes on and on).
That said, I've read Litz' book. G7 makes more sense so that's what i use when i can.

 

[Lowlight]

Understand that the software and modeling used is based on Point Mass... Point Mass as a model favors one G Factor over another... in a word it's freeware from a long time ago.

If the model you use favors something it makes perfect sense to use "that curve" when possible. (it is not always available) with iPhone Apps and many other pieces of software, you will find G7 works well if all your other variables line up. Because the software is assuming your bullet is following G7 curve. (these programs are not very powerful, there is a lot of flat rate values inserted to make it work) However you can easily "bend" the model by using G1 by Stepping or Banding it... putting in more than one BC value. Software like JBM will do this for you if you select the G1 value, you'll notice there is 3 BCs insert and not 1 Average. This helps the software understand your curve better.

Interesting we went over 50 years using G1 and in fact G7 has been available since the 1950s and it was only until the 2000s we started using it. Aberdeen is actually starting to use G8 too... Bryan is doing excellent work around G7 because the software is now available to take advantage of the model. So when given the choice with an App, G7 "should" work better, not always the case, so that brings a lot into question. Why doesn't it if the model is so cut and dry... well those variables are part of it.

People can ignore the statements about other software, and other models that only use G1 like FFS, which has been proven to be one of the best. The next piece of software Patagonia, can also use G1 but has chosen to include G7... Before his death talking to Gerald Perry who invented ExBal one of the first consumer level Ballistic Calculators, he dismissed G7, much like FFS does... Was he right ? Maybe, maybe not... Bryan continues to forward G7 with great success, and as long as we have access to low cost Apps using Point Mass, G7 will continue to work well. But not everyone agrees.

The world didn't suddenly start hitting targets when G7 numbers started trickling out, to this day not all manufacturers will give you BCs with a G7 value so there is definitely more to do. Also you'll start to see banding / or stepped numbers for G7 to make it even more accurate. This asks an important question, if the G7 average is good, and G7 banding is better, and if G1 was good and G1 Banding is better... what is the difference ? Well the software used, that is ... if its the same amount work, but with less data, you have to ask the ?

This is example of the automatic Banding or Stepping JBM Does all by itself to better adjust the Point Mass Curve to work with G1 Note the BC Values at the Top

 

[damoncali]

I disagree with your description of the point mass model in some ways that probably aren't worth getting into, but you bring up an interesting point in regarding banded BC's.

Using banded BC's is nothing more than a mathematical kludge to correct an inaccurate drag function. Of course, they're all wrong to a degree and so you can improve things by using multiple BC's. If you choose to do this it literally does not matter what drag function you use as long as you're willing to tweak the BC enough to correct it. Picking the "right" one will simply require less tweaking. But if you're willing to enter 1000 BC's, you can use the drag function of a cube and it won't matter. The entire point of a BC is to not have to enter more than one number.

But just as computers have made it easy to solve the point mass equations, they also make it easy to enter lots of numbers...

The logical conclusion of this process is a bullet-specific drag function and *no BC at all*. Given recent improvements in technology, I do not think that is out of the question in the future. It is just matter of cost effectively measuring drag for each bullet across the relevant velocities.

 

[Lowlight]

The benefit of the G7 model was stated as, "a better average based on testing done"... so this one number using the Point Mass software was supposed to be a truer representation of the flight of the bullet. (Understand I am paraphrasing a lot) The G7 average was meant to be more "accurate" than the G1 average using the same piece of software.

But as we all know, BCs are not always correct, variables are not always accounted for, nor can they be, and the tests were done by one person with limited resources. (Look at the images in the book) We cannot say, every rifle with a 1-12 twist and a 24" Barrel will yield the following results : A + B = C, In many cases it equals B+, or C- or even D... No two barrels and bullets are exactly the same, or better, no two combination of barrel, bullet and shooter is the same. So that skews the equations.

While Sierra may advertise a G1 .505 for a 175gr SMK, and Bryan may have tested it in his rifle and found .475 is a better average, for years many of us have used .496 for the same bullet. Does that make any one of them right or wrong ? Basically they are all the right answer in the proper context... at 3000fps Sierra is right, out of Bryan's gun on that day his number is right and for the last 40 years .496 has served many people well and has proven correct.

Under the same conditions, Bryan advises a G7 of .243 for the 175, for me that maybe .239, for someone else, .245, still, because it is written down and advertised as such, people feel .243 is set in Stone... but clearly History with G1 has shown us, nothing is set in stone, which is why we band.

Apps are a tool, they are convenience device, so giving people 1 good average makes perfect sense. While marketing may blur the facts, what they are saying is, "if you use this with your MV, Sight Height, and Bullet Type & Weight under the current conditions we will get you close enough to hit your target somewhere close"... unfortunately people feel because someone can say, "I got "X" Number of 1st round hits out to 1000 yards by using the G7 value of .243" then everyone will get the same exact results without any more effort than plugging in the basics. Add to the fact, we are giving an avalanche of data that backs this up by people who are working towards a specific end, we have debates like this with statements that say, "G7 or else you will miss at 1000 yards"... then the anecdotal data flies, "i use G7 with my $9 App and it works perfect... conclusion winner ! When really, it will vary every day by a number of people.

It's an average designed to work in low cost software powered by Freeware... if you bought a version of Adobe Photoshop that was powered by Freeware and cost $9 compared to Adobe's asking price of $500 you would not expect it to work the same. Still people expect miracles out of an App... especially when the App knows very little about your or your system.

When given the choice, with an App, I use G7, if I am using FFS or Patagonia, which both are installed on my Trimble Nomad, the primary device I use, I use G1 religiously, and beyond 2000m I have used it too great success. The Apps I use to double check things on the fly, the Nomad is what I use when it counts.

 

[damoncali]

I think you're throwing out the baby with the bath water.

There isn't anything in the point mass model that prevents you from creating your own drag function - it's trivial on the software end. In fact, I wrote a point mass solver that does that myself - no reliance on standard functions or BC's at all. I bet I could throw it up on a website for free today and nobody would use it since nobody wants to go through the trouble of figuring out what exact drag function is. That's not a condemnation of point mass (which is pretty much a restatement of Newton's Laws) but of the difficulty in measuring drag.

Or maybe I'm wrong and I should start a software company.

 

[sharac]

Omg simple paper and pencil and one freaking load (instead of 10) and a little bit of work (aka shooting) will give you BC, GC. FC and CC in all available models from 1-infinity and as said already every ballistic program with any model given correct variables (shooter, enviro...) will get you to "paper" first time and paper and pencil will get you there for ever. Why does it have to be in every country this mathematical vs statistican discussion (math person will gnaw statistician to death because something does not add up to a Nth decimal and statistician will go bone dry shouting to mathematician that for practical application Nth decimal is less important than last years snow) which leads nowhere.

 

[Lowlight]

No the point is, one is not necessarily better than the other, as I said I use both.

If you are doing the same exact amount of work and get the same exact answer downrange, it renders the debate mute. If either are equally acceptable, or equally off, then the question really becomes how much effort do you want to invest in it to "true" the number, on either side.

People are looking for a shortcut, if you said in order to use "This" App you must:

1. Calibrate your Scope, testing the tracking and adjustment across 100% of the useful range

2. Get your Muzzle Velocity Average across no less than 40 rounds under a variety of conditions

3. Estimate a new BC for your rifle and Bullet combination using new BC not manufacturer supplied numbers

4. Use a Handheld Weather meter at your Shooting Position Only for Environmental Conditions

Then, input that data in order for it to give a better starting point for your software, people would move on to the next app. But honestly that is what it takes to do it right just give you a proper starting point... Again, A proper starting point.

But the truth is closer to

1. Pick Bullet from library using all stock data
2. throw in a muzzle velocity
3. Let phone gather weather data

Shoot... Hit Target, Win Match !

 

[demolitionman]

But the truth is closer to

1. Pick Bullet from library using all stock data
2. throw in a muzzle velocity
3. Let phone gather weather data

Shoot... Hit Target, Win Match !

^ this is me, guilty as charged...except for the Win Match part lol!

 

[damoncali]

But the truth is closer to

1. Pick Bullet from library using all stock data
2. throw in a muzzle velocity
3. Let phone gather weather data

Shoot... Hit Target, Win Match !

A confession: Despite my interest in ballistics as a hobby and my belief that understanding it can help improve gear and techniques, I don't even use my own software for much more than exploration and bullet selection. My truth is:

1. Look at the experienced guy next to me
2. Copy what he did
3. Shoot... Cuss... adjust. Finish in the middle of the pack!

 

[Rob01]

But the truth is closer to

1. Pick Bullet from library using all stock data
2. throw in a muzzle velocity
3. Let phone gather weather data

Shoot... Hit Target, Win Match !

Actually I do it just like that except I do all my data before going to a match and print and laminate the sheets using JBM. I use the location elevation and run charts in 10 degree temp changes according to what accuweather says will be highs and low. Don't use any sort of program at the match and I still seem to hit targets. Hmm how do I do it?

 

[Gray]

A confession: Despite my interest in ballistics as a hobby and my belief that understanding it can help improve gear and techniques, I don't even use my own software for much more than exploration and bullet selection. My truth is:

1. Look at the experienced guy next to me
2. Copy what he did
3. Shoot... Cuss... adjust. Finish in the middle of the pack!

That funny right there...

 

[Lukas Koukal]

Just posted this in the Shooter app thread, but figure it could help some here, too. Have to agree with Frank, if you don´t, invest your own time and TEST your beliefs by the bullet´s flight.

Got into another interesting que:

Comparing combined G1 coefficient with G7. The bullet is .30 Nosler Custom Competition 155grs, which is exact copy of Sierra´s original #2155 Palma bullet. It´s loaded to Mv of 2850fps.

We can get three different G1 coefficients for dropping speed from here: http://www.sierrabullets.com/bullets/BallisticCoefficient-rifle.pdf

.450 @ 2600 fps and above
.443 between 1800 and 2600 fps
.417 @ 1800 fps and below

We can use .213 G7 reported by Bryan: http://www.appliedballisticsllc.com/index_files/S155grPALMAbullet.pdf

Now I´ve created 2 ammo profiles in my app, only difference being the ballistic coefficients used for calculation.

I´ve input some average atmospheric conditions and these are the results:

G1: needs 11.2Mils for 1000m shot and reports transonic at 1025m.
G7: needs 11.8Mils for 1000m shot and reports transonic 925m already.

The difference is not through the roof, but one would be a miss on steel. I´ll report after Saturday´s match - real atm. conditions, corrected actual Mv for the day, observed necessary correction from 600 - 1000m and how close both calculations were.

Results to the experiment:

Both calculations were within .4mils at 960m sight-in (1050yards). We had a realy hot day, over 30°C in the open (+-80-90F); I had to adjust the MV using the Shooters´ muzzle velocity tool -> came out at 898m/s for the G1 and 900m/s for the G7 (2946fps and 2952fps respectively).

After truing the MV according to the observed hits (and having had confirmed 100m zero first), BOTH G1 and G7 calculations gave spot on elevation dope as verified across the course from 1000m down to 600m (1093yds to 656yds).

Personal observation - garbage in, garbage out. As long as I avoid that and pay attention to details, both systems work to equal precision. The preference to one may best be because of availability of input information, thus giving more options to the shooter... and that´s it.

 

[serater]

scope height is absolutely critical with g7

 

[TiroFijo]

Scope height has a very minor effect, and it is the SAME with any ballistic program... it is a simple math correction to correct sight offset, that is added (but totally independent) to the ballistic predictions.

 

[pucker]

That funny right there...

Funny, but that describes me shooting next to you at Woody's a couple months ago! Surprised you didn't hear the cussing part.

 

[MajorHeadTrauma]

Tag for later



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