Trajectory calibration question

[Firearrow]

i amshooting a 300 WM with 190gr Bergers, an they are going 2980 per my Shoot'en Chrony (don't laugh it's all I have). So I am zeroes at 200 yards. When I went to shoot 300 I was high by 4.5 inches, about 1.0 MOA. At 500 I was averaged 5.5 high.

So I use the trajectory validation on the G7 web page. It tells me that my corrected velocity is about 3250.

So the question is, is my shoot'en chrony that far off, or are the numbers off of G7 page just the numbers I need to use and they don't nessicarly mean that's what I am really shooting. This has go me all mess up in the head. Can't firgure this out.

 

[406precision]

The trajectory validation should really be done at a min of 800 yards...to get reliable data. Some guys skew the bc some skew the velocity...we try to get solid data at the longest distance we can get reliable data based on current conditions and go from there with the velocity verification .

The chrono is just an educated guess in my book too many variables just enough information to get you on steel and then you field verify your drops and confirm them with spent brass and burnt powder lol

Jordan@406

 

[Firearrow]

I will try and find an area tomorrow to get 800 or at least as far as I can. The whole thing about being 4 inches high at 300 is the hard thing for me to wrap my head around. I did it three times with the groups all the same. Shooter says 2.0 MOA up from my 200 yard zero, and in reality it's more like 1.

I'm starting over. Confirm my 200 again and go out from there. Funny thing is I'm leaving on Monday for a week for the closing week of our B zone. After all this confusion is setteled I bet I don't see anything. Guess a rabbit or squirl will work in a pinch, but I have a deer and bear tag to fill.

 

[WildRose]

I've always found it best to use three different ranges for validating drops.

Try 200, 500, and then one more at least 600yds out. If you can get things adjusted in your program to match those three you're going to be extremely close out to 1,000yds, maybe a bit further.

If you're planning to shoot beyond 1,000 the game changes quite a bit because when bullets get into the transonic and then subsonic range they tend to behave much differently.

If you're shooting at such ranges then you'll need to validate using at least two points beginning with where the transition begins and one or two more during the subsonic part of the flight path.

Once you have good data to work with print yourself up some drop cards and keep them with the rifle and you'll be pretty well set.

 

[Firearrow]

I've always found it best to use three different ranges for validating drops.

Try 200, 500, and then one more at least 600yds out. If you can get things adjusted in your program to match those three you're going to be extremely close out to 1,000yds, maybe a bit further.

If you're planning to shoot beyond 1,000 the game changes quite a bit because when bullets get into the transonic and then subsonic range they tend to behave much differently.

If you're shooting at such ranges then you'll need to validate using at least two points beginning with where the transition begins and one or two more during the subsonic part of the flight path.

Once you have good data to work with print yourself up some drop cards and keep them with the rifle and you'll be pretty well set.

To be honust I just want to figure out what I am doing wrong. Either in the input in my app, my shooting for , ect. I'm leaving on Monday to hunt for a week for the closer of our B zone deer season. I just want to have confidence in my rifle/app so that way I know it's all up to me. One way or another I have made a mistake, I just need to fix it.

Going to shoot tomorrow and reconfirm my 200 yard zero. Then shoot 300, 500, and hope fully 700 or 800 if I can get it. Just need to find a spot in the NF somewhere.

By the way thanks for the reply.

 

[WildRose]

To be honust I just want to figure out what I am doing wrong. Either in the input in my app, my shooting for , ect. I'm leaving on Monday to hunt for a week for the closer of our B zone deer season. I just want to have confidence in my rifle/app so that way I know it's all up to me. One way or another I have made a mistake, I just need to fix it.

Going to shoot tomorrow and reconfirm my 200 yard zero. Then shoot 300, 500, and hope fully 700 or 800 if I can get it. Just need to find a spot in the NF somewhere.

By the way thanks for the reply.

It may or may not be a mistake. As much time and effort as goes into programming these apps there's errors built into all of them due to all of the variables.

Check the simple things like scope height, elevation, barometer etc as all of those can affect the calculation.

Chrony's too have errors built in, none of those guys like us can afford are infallible.

Verify your drops then play with velocity and BC on your program as needed to make it work as close for you as possible. Remember too that BC's are not really static, they vary with velocity. The G7 BC's seem to work best beyond 600yds so if you have the G7 BC for your bullet go with that.

Don't let it stress you out, stress tends to have negative impacts on shooting performance.

 

[ShootnMathews]

Everyone has there own way, but I usually will zero it at 100 yards when I'm working on the traj. Then I shoot 475 and 725 but those odd numbers at just how the mountains fall here. In another location I shoot at I do 500 and 800. The farther you verify it the more precise it is in my opinion. For example I cand adjust the velocity to be close enough to hit within an inch or so at 500 and call that good but the few fps that I'm off can translate into several inches off target at 800 or 900 yards. After I'm done working on trajectory, then I will adjust the zero to 200 or 300 or whatever using the number of click the the program tells me too. That way all of the drop data matches up still.

 

[NWmissouriman]

I was having similar issues as you, only on the low side. I was even using a Magneeto. I zeroed at 100 and then shot at 400, 600, and 800. Even distances seemed to make it easier. I took pictures of the target at each distance with a tape measure stretched across the target. I was able to use the trajectory validation feature to adjust the velocity and the BC (slightly) to make my drops come out like they were supposed to. I used to zero at MPBR, but I have found it to be easier to zero at 100 in case I'm hunting in completely different extremes from where I sighted in at. Plus if you zero at 100 and set your zero stop, you can always turn it up 1.0-2.5 moa or so if you are hunting where you sighted in at and you won't to worry about dialing or holding over out to 300 yards or so if you don't want to. As stated earlier, there are errors in almost everything and the best thing you can do is shoot to validate. I was pretty surprised that both the magneto and the Berger G7 BC were both different from what I thought they were. Good luck!

 

[el matador]

Maybe a dumb question, but is your scope MOA or MRAD? If you're coming up 8 clicks and you've got a MRAD scope you're moving around 2.75 MOA. That would give you 2-3" of error. Just something to check. Also, for your 200 yd zero are you actually shooting at 200 or just sighting a bit high at 100? That could account for some error as well if your sight height or zero are a smidgin off.

 

[Firearrow]

Well I just got back and everything was fine today. My last outing must have been me. Might have been me choosing a bad shooting position. I was laying down hill and my rifle was aiming up hill. Shot a bunch today, adjusted my velocity a touch, and I'm a happy camper. Thanks to everyone who helped me out on this. I really appreciate it. Now I just need a Blacktail to step out and let me see him.

 

[WildRose]

Well I just got back and everything was fine today. My last outing must have been me. Might have been me choosing a bad shooting position. I was laying down hill and my rifle was aiming up hill. Shot a bunch today, adjusted my velocity a touch, and I'm a happy camper. Thanks to everyone who helped me out on this. I really appreciate it. Now I just need a Blacktail to step out and let me see him.

That will certainly do it. When shooting uphill it's real easy to get your eye above centerline which then raises your POI.

It doesn't matter how experienced you are as a shooter it's the basics that usually bite us in the ***.

Glad you got it figured out. Just pay attention to that good consistent cheek weld no matter what your position you are in and if you can't achieve it, change positions.

 

[Firearrow]

That will certainly do it. When shooting uphill it's real easy to get your eye above centerline which then raises your POI.

It doesn't matter how experienced you are as a shooter it's the basics that usually bite us in the ***.

Glad you got it figured out. Just pay attention to that good consistent cheek weld no matter what your position you are in and if you can't achieve it, change positions.

O so true. No matter how much range time I have, that can't off set time in the dirt. When I get back from my hunting trip, I have a box from Nachez with 210gr Bergers that I need to work up. I can already see the look on my wife's face.

Thanks again fr the help.