Confirming Drops

[MachV]

The guys where wondering where they would have to aim to hit a few deer last week. My answer was a simple show up next summer and we will work on it.I conned myshooting partner into takeing a 1000 yard shot @ a MOA rock. he knew his point of aim for 850yards so he aimed a little higher and sent a round 4' high, he did not factor in the rock was 300 yards lower than we wherelightbulb He put his 850 yard aim point on that 1000 yard rock and hit the right hand edge, although there was absolutly no wind where we were there was a slight breeeze running on the rock side of the canyon....The grass was telling him but he was not lisining! When the other guys called it luck he sent another round aiming @ the left side of the rock=no more rock!
The whole gang is hooked and am looking forward to many more rock killing sesions.

I think once we have our velocities, BCs, click values and programs figured out we will find we are still one step behind what Ernie is talking about
The wind, sun and mirage can really put a new spin on things once you think you have it figured out!

 

[RDM416]

I always confirm my calculated drops and simply will not attempt a shot at an animal at distances further than I have done so.

I have tried several ballistic programs and found that they all pretty much give me the same answers. I have also found that at distances beyond 700 or 800 yards they are often off enough for a miss on a deer sized critter.

As we all know, 1/2 moa at 1000 yards is 5", a full moa is 10". Seldom will my ballistic programs get me to closer than an moa at 1000. Maybe the rest of you don't have that problem, but I do. I attribute it to changes in BC as the speed of the bullet changes...... don't know for sure, just know that my program seldom matches up with real shooting data.

I start out with a 3 shot group at 100, then move to 200, then 300, 400, etc. When first setting up my dial up chart I will typically shoot 2 shots at each range, assuming the shots are falling where expected. Once I have my chart done out to 1000 I will put fresh paper on my target stand and reverse the process shooting 1 shot at each range back to 100 where I expect to be dead on. I will repeat the 1 shot at each range from 100 to 1000 4 or 5 times usually over a period of several days or weeks. I keep each target and compare them all, keeping track of all the environmental data and the velocity of each round. I use all that info to fine tune my dial up chart.

Obviously, things change with elevation, temperature, etc., but I now have a baseline that I KNOW is perfect for a given set of conditions. With that plugged into the ballistic program, I am much more comfortable with the minor changes in my dial up from local weather conditions.

I am fortunate to have a range at my house where I can shoot out to 1200 yards. I know many of you do not have that luxury and have to rely more on calculated ballistics data. For me, I rely on my ballistics programs to get me in the ballpark. I just don't think there is any substitute for actual "real world" data. Maybe that is just the engineer coming out, but I want data, real data..... not just what the computer said

 

[mo]

""I have tried several ballistic programs and found that they all pretty much give me the same answers. I have also found that at distances beyond 700 or 800 yards they are often off enough for a miss on a deer sized critter.""

RDM416
I have found the same as you on multiple rifles too. The ballistics programs will get you out 725 yds anything passed that will result in a miss. All the rifles I've shot always hit higher then what the program said.

 

[4xforfun]

I had a wierd experiance today....
Went out this morning to conferm all of my 300 yard zeros.....overcast....started at 37 degrees and finished at 41. Baro was steady at 29.63. elev 952. I also used my ced 2 with I R sky screens.

After conferming my zeros, I set up at 600 do do some preliminary drop testing....just leave the scopes alone at the 300 yard zero and measure the drops. now.....the sun has started to peak through, still zero wind, so mirage was strait up. My chrono quit working because of the angle of the sun so I put it away. Shot all four guns....My 1 K comp gun, My custom hunting gun, a friends 1 k comp gun in an A5 stock...all 300 wbys with 210 bergers, and my little dasher.

I went back to the shop to check the drops/chrono readings against my sierra program. To get all of the numbers to come out I had to bump up the FPS on the program by as much as 75 FPS. Now, I attributed this to the mirage...could have realy affected my sight picture. I printed out the adjusted info for each gun anyway.


Went out again this afternoon.....Bright sun....59 degrees, baro still holding at 29.62. I shot all four guns at the 600 yard target using the adjusted computer generated sheet. All shots were 1 - 1 1/4 moa high......all four guns.

Went back to the 300 yard target (also still standing from this morning......all four guns were 1 moa high. I just left the guns at thier morning zero. We messed around at 600 -900 yards, still using the adjusted computer dial up sheets MINUS THE ONE MOA and hammered everything we aimed at. Just before dark I went again to the 300 yard target.....now overcast , temps falling light fading.....and my impacts were all still 1 - 1 1/4 moa high...all four guns!!!! I re zeroed all four guns...again.... with all of the remaining ammo and packed it in.

Added info.....I used the dual inch/moa feature on the sierra program....I used MOA dial-ups for the three nightforce scopes and inches with the lone Leupold.

I now want to quit shooting and take up quantum physics....gotta be a whole lot less frustrating!!!!!

 

[SBruce]

4X,

If I am understanding you correctly......You weren't able to confirm by cronograph that the 75 fps was a fact or not?

Another question, when you were shooting 1 moa high, was that after you added the 75 fps to the program velocity?...........Still shooting high in relation to program??

One more, did you change the temp in the program to account for the 59 degrees prior to shooting 1 moa high at 600 yds, or was it still set at the 41 degree temp from the morning??

Not trying to second guess your methods, just hoping/trying to figure things out a little more.

 

[RDM416]

MO, That is exactly what I typically see, again on multiple rifles. The ballistic programs always end up with me shooting high at ranges over 700. Once I am comfortable with my measured dial up chart, I will adjust velocity or BC in my program to make them match.

4xForfun, I had a similar problem and eventually narrowed it down to the scope slipping in the rings and/or the rings slipping on the base. I would get my 100 yard zero, shoot all my dial ups out to 1000 then find my 100 zero had moved up an moa or so. I eventually had to pin my rail to the rifle and use 2 sets of rings to stop this, but I am shooting a much larger rifle. Although I would not rule this out, it does seem strange that you have several rifles doing the same thing.

 

[4xforfun]

4X,

If I am understanding you correctly......You weren't able to confirm by cronograph that the 75 fps was a fact or not?

Another question, when you were shooting 1 moa high, was that after you added the 75 fps to the program velocity?...........Still shooting high in relation to program??

One more, did you change the temp in the program to account for the 59 degrees prior to shooting 1 moa high at 600 yds, or was it still set at the 41 degree temp from the morning??

Not trying to second guess your methods, just hoping/trying to figure things out a little more.

I did not conferm the chrono readings.....BUT 3 of the 4 guns have been in my stable for years, shooting the same loads, with tons of chrono readings. The forth is a new load I am working up for my match gun...been chronoed a half dozen times. All numbers pretty much match yesterdays numbers. This is just the first time I actualy measured actual drops for a while.

I zeroed the rifles....with chrono data....shot and measured the drops at 600.....plugged the numbers into my Sierra program....had to add about 75 FPS to make the actual drop measurements match what the computer was saying......proceded to print out the drop sheet WITH THE 75 FPS ADDED IN, just to see........went to the range and had to take another 1 moa out to make direct hits out to 900.....I was 1 moa high with all four guns. Had I not fudged the numbers in the program that morning I would have bee a lot further off that 1 moa.

I did not enter the increased temp into the software, but just checked what the drop differance is between 38f and 59f........18.68 low vs 18.6 low at 300 yards...all other things remaning the same.....1/10 of an inch...not 1 moa.

I tell ya....I'm a little freaked out....been shooting long range forever.

I fully expect things will all go back to normal next time out.

This reminds me of countless conversations with my brother....HIM....we need to shoot the distances (He does't shoot near as much as I do). My responce...why waste the ammo....it's all math and science....the numbers are never wrong!!!!!

WHOOPS. lightbulb
But, what the hell. Now I have (another) excuse to go shooting!!!!

 

[SBruce]

I fully expect things will all go back to normal next time out.

That's what we found when we shot on three different days. We had to keep fudging the velocities in order to get the program to match the drops.

One day it was high, the next back to where it should have been the first day, and the next was high again....WAY high. Temperature didn't vary by an abnormal amount for October on any of those days, but there was a difference in cloud cover, temp, wind and amount of visible mirrage.

That's the most frustrating part, if it would stay consistant we could deal with it. This is the reason I am wondering if Mirage and Light variations have more effect than we all realize???

Where are you Ernie??? Can you confirm on light/mirage some??

 

[Ernie]

First of all, I would not assume that I am way ahead of you guys in this.

What I did not check (should have) was the BP each day.
My second mistake is I have not kept good notes.
If I had done this it would have given me more hard info-So shame on me there.
I think the next level is all about tedious notes, and paying attention to all the little things until you begin to see trends. All those little things can and do make a difference.
Since I am shooting bullets about 250-300 fps slower (specialty handguns) than what you guys would get with the same chambering, I need to pay even better attention to the conditions to ensure first shot connections.
I think the Big 7's and 338's (30's to I am just a 30 cal fan) have a real place for LR hunting in that the bullets you have to choose from give us more fudge room for field shooting.
I think it is important to have a some smaller cartridges to practice in wind for because of cost, longer barrel life, less recoil, etc.

I did see a correlation between sunshine and cloudy, with sunshine shooting higher (1/4 less MOA needed).
Also, on another day I kept shooting high-Had a head wind that day.

Mirage bends light and causes us to think we are shooting at one spot only to be hitting another.
One way to use mirage to your advantage is laser a spot on the ground, get your distance, then adjust your parallax for that distance then move your scope up and now you know what the mirage/wind is doing at that specifc distance. You may have to move it slightly out of focus to see the mirage better, but this is a way you can get your different wind dope when you do not have other wind indicators downrange.

I got killed the other day at 800 yards, as I went 1 MOA right, when after I shot I should have moved one MOA left. There was something going on that I missed. Again being in a hurry, I did not take the time to try to figure it out better. Two other guys who shoot LR were with me, and they both missed it/read it like I did.

I think these small variances show up at shorter distances 400-600/700 yards, but some times we assume it is other things (like our shooting that day). A 1/4 or 1/2 MOA at mid-ranges is not a terrible, but it will sure mess you up at longer distances.

At times we are so happy to just make a hit at long-range we are not making notes of where that is from the last time we shot.
I should go down the range and measure my vertical hits each time-That would be so much more telling.

Topography of terrain is also huge when you have wind-It can really change your vertical too.

On a scope note, I feel I have real advantage using Holland's ART reticle, in that I never dial more than 1.25 MOA for elevation until I get beyond 30 MOA.
I effectively eliminate those problems, plus the rotational mistakes that are all so common for those of us who dial everything.
I have several scopes with ART.
If you have any questions about it or this discussion, you can always give me a holler: 307-257-7431

 

[SBruce]

Thanks for the reply Ernie

Good to hear some confirmation and that someone else has seen differences on cloudy vs sunny days. Since the programs don't account for this, I guess good record keeping and practice is about the only way to quantify the amounts of difference do to lighting.?

Up till recently, I've mostly used holdover marks in the scopes for shooting too. (out to 600 yds with 22-250 anyway.) So the dialing everything in is a new variable to contend with for me.

Thanks again Ernie, I'll give you a call someday. Would be good to get together and shoot sometime. I'll probably wait till I receive one of the new rifles though, because I don't yet have one that's really capable of 700 to 1K stuff. We were using a friends 338 Edge when I saw these variable changes in question.

 

[4xforfun]

Yep...ive seen the sun /cloud thing happen many times. When I shoot 1000 yard comp, during the sighter period, I always take a shot when I see the sun pop out or hide, even if it is only for a few seconds. The bigger the light change, the bigger the impact change. I can't read wind for CRAP, but, during a match, with say 15 -20 seconds left in the sightor period, I always look up to see if a small cloud is about ready to cover the sun, or visa versa. It usualy protects me from the "W T F's" that I see with some other compeditors after missing a light change.

But.....there are no sighters in LR hunting!!!

In my situation, I did my last 300 yard zero/re-zero right before dark and the skys were a dark overcast....still 1 moa high!

 

[SBruce]

4X,

I'd be curious to hear about your next trip to the range. Wondering if everything really did "go back to normal" or if something changed again.

Thanks in advance.

 

[fatrack]

The temperature of my loaded rounds can really change my POI.

Next time you are out shooting do an experiment- stick a round under your armpit for a couple of minutes and then add it to your group and see how much of a flyer it is.

Even with temperature insensitive powders I have been amazed the difference temperature makes in my come ups.

 

[SBruce]

The temperature of my loaded rounds can really change my POI.

Next time you are out shooting do an experiment- stick a round under your armpit for a couple of minutes and then add it to your group and see how much of a flyer it is.

Even with temperature insensitive powders I have been amazed the difference temperature makes in my come ups.

Good point, Ammo temp was another one of my questions..........possible velocity changes that can't be predicted by a program. I had wondered if the ammo in question was getting warm enough to make it shoot higher and higher. The powder being used isn't supposed to be temp sensitive, but it sure seemed to be shooting higher on the sunny days..??