Target Knobs vs Clicks vs Alt. vs Temp

[Guest]

Had some interesting results these past 2 weeks. It basically solidified my feelings that target knobs just don't work or won't work in all conditions.

a few of us had to re-evaluate our dope on some of the rifles. Even my beloved 7wsm was a 1/2" low at 100 yards.

now that doesn't seem all that much until you go to 500 yards. This could be an easy miss.

After some of us missed easy shots. We set up a steel gong and re-evaluated our dopes. After that it was back to business as usuall.

As best we could tell the changes were from Alt. and Temp. We had a cold front move through and the temps dipped into the upper 20's and low 30's . Most of us had dope for 60*-70* +

This isn't a slam on the guys who make the BDC knobs. Just some real word data that contradicts what the computers and ballistics programs might say. Truth of the matter is. I wouldn't trust the knobs or my drop charts until I confirm the data at the place and alt. I am hunting!

take it FWIW

 

[Boman]

Ric,
Thanks for reporting this back to us. I have a few questions. Did you guys go ahead and shoot your rifles to out the desired long range for ex. 500yds? If so did you find that that your about .5moa off all the way to 500? meaning did that change stay consistent or was it more or less at longer ranges? I'm just curious. Also did you notice this more or less with Chris's rifles since his were probably sited at a lower elevation? Do you think the differences would cause a miss on a large buck or elk?

I think what your saying is what has been said by you and others many times.. Just shoot your rifle alot and then shoot it again once you arrive at your hunting locale. Thanks

 

[Charles A]

Thats why if your going to be hunting at diferent places with different ENV. you have to get a program that calculates the difference in POI, use a temp insensitive powder, and shoot with different BP to verify. Also was the light conditions different then when you zeroed? We notice about a half MOA diference between bright sunlight and overcast days, though that depends on the shooter.

I agree on the BDC knobs, but a 1/2MOA isnt that much, and the POI is going to be .5MOA off from POA no matter what the aiming method.

 

[Ankeny]

Environmental conditions that result in a .5 MOA vertical shift in a 100 yard zero wouldn't make me miss an "easy" shot. Just how far do you guys consider "easy"? /ubbthreads/images/graemlins/grin.gif

When my "dope" goes to hell in a handbasket it's usually because of mirage rather than elevation.

 

[Mysticplayer]

Ric, I face the same issues in temp swings living in the wooly north. Changes in drop chart are not necessarily the fault of the scope.

I have found some barrels to change POI when they get cold. However, zero returns as the barrel heats up. Stocks can change due to temp and humidity - composite, plastic and lam stocks are usually pretty good. Ammo can change POI due to changes in powder and primer burn. I use Hodgdon Extreme powders and that seems to help with this issue.

Changes in muzzle velocity and conditions can also affect the BC of a bullet. That in turn changes your drop chart.

The clothing that you wear can affect length of pull, eye relief which can affect parallax, and how the rifle recoils. I do quite a bit of testing in the winter so that I am as bundled up as I hunt.

Finally, what you see!! Air density, humidity, and light all play with the image you see through your scope. Sighting/practising in air that has very high humidity then shooting in cold dry air will show different results simply because of the changes in what you see.

All the above plays a part in changes in your drop chart. You are right that every effort must be made to shoot in the new environment you are hunting in. A quick zero check isn't a bad idea if the rifle has seen some distance in a cargo hold or trunk.

If in doubt, a spotting shot will 'correct' for all of these little changes and confirm your impact.

Hope this helps.

Jerry

 

[Guest]

I guess that is my pont you can't rely on all the gadgets and bells and whistles... you have to shoot! Shoot alot! in all conditions and everywhere you can.
I darn near got asked to leave this board for arguing a point about BDC knobs and I still hold fim to my statements about them . I feel in this sport you cannot rely on such a "non adjustable" item. I live mearly a few hundred feet difference in altitude but even my dope was off by a bit. I feel the weather changes etc. all play a vital role in why I was off by .5"
This sport is controversial enough with any mistakes. Once we make a mistake it only fuels the fire.
Nothing beats practicing every moment you can with your choice of weapon, learning everything you can about it. Once you do set limits and standards.
I passed on a 800 yard shot that I know I can make day in and day out. However, the wind would not make up its mind wether to blow hard or soft. The conditions changed every 5-20 seconds. Chris and Steve knew I could make the shot but respected my "self control" and limits of my ability during those conditions. I called it off and we moved on to another day.
I spend hours and hours ( more like days and months ) shooting every year. I learn stuff every time I go out. I was really supprised to see the minor differences in the dope once we arrived at the area we were hunting. We all need to remember that minor differences at 100 lead to big differences beyond that...

 

[Michael Eichele]

Once again this is why I ALWAYS find a zero at 300 yards. 1/2" off at 100 yards and you are screwed at longer distances. When you find a zero at 300 yards, if you are 1/2" off center it wont effect the POI more than a very negligable amount at longer ranges. I havent noticed much of a zero change at 300 yards either when transitioning from the range to higher and colder elevations. 300 yards allows the "bugs" to be ironed out so to speak. When using this tecnique I have found clicks to be deadly accurate. That is just what works for me.

The point here is something will work for all of us. We just have to get out and practice and figure out what works us.

PS, When a rifle is zeroed in bright sunny conditions or vice versa, in cloudy conditions, the POI WILL change due to optical differances when the light conditions change. It is ussually about .5 MOA up or down and .5 MOA left or right. In other words if you sight in on a bright day and shoot tomarrow on a bright day it WONT be affected but if you shoot on a cloudy day you will see a POI differance. Zero in sun and shoot on cloudy the bullets will hit high and left, about .5 MOA

Regards!

 

[Mikecr]

I don't agree with the DON'T THINK - JUST SHOOT AlOT approach. In my view, you'll learn far more thinking than shooting. You can learn what works and what don't right up front, by reading books and searching forums. This includes understanding what affects POI. All without spending a dime, or taking a shot.
Your question HERE is not an indicator of more shooting needed. It's an indicator of more learning needed, and your willingness to do just that.

Shooting is easy. Understanding the whats, wheres, and whys of it is hard work.
Don't believe me? Try it.

 

[Michael Eichele]

I agree with you MikeCR. Many things Ive learned were from reading or talking with others. Many things have had me scratching my head for months or even years untill some research made it oh so clear! Thats not to say that practice isnt important. Its hard to replace raw experiance, but it is about equally important to understand why things happen as you stated.

 

[Guest]

[ QUOTE ]
I don't agree with the DON'T THINK - JUST SHOOT AlOT approach. In my view, you'll learn far more thinking than shooting. You can learn what works and what don't right up front, by reading books and searching forums. This includes understanding what affects POI. All without spending a dime, or taking a shot.


[/ QUOTE ]

I do as much of this as anyone.. read, search, post , ask questions etc.
I have as many gadgets as the next guy and rely heavily upon the palm and a-trag system.
My point is you cannot get good and accurate without shooting. You can't rely upon a knob to do you work. I don't care how much you read, learn and ask questions if you are not out shooting ... you'll never get good.. PERIOD

 

[Mikecr]

Ric
I didn't mean anything negative, and I completely agree with you on the limited merits of BDC.

I guess I'm just overly sensitive to any balking of technology or non-traditional approaches. I hear BR shooters and weekend gong hitters implying that ballistic programs don't work. Gotta carry a log. Stability calcs aren't "real", just shoot faster.

It's like racecar drivers(amature or professional)implying that volumetric efficiency is hogwash. Just drive.
Yes, some actually play a roll in their engine design. But not many. And you and I won't learn it going roundy-roundy.

 

[Mysticplayer]

Ric, you know what the worse part of all this is?????

Once we get all the bugs worked out, feel completely confident in the rifle, load and drop table...

We have burnt the barrel out /ubbthreads/images/graemlins/grin.gif

Jerry

 

[Ian M]

I shot long for several hours today. My partner wanted to check the drops that we shot this summer in anticipation of the upcoming hunting season. Just like you mentioned, all of his drops were out by about one MOA from the summer numbers. Wish I knew what caused the change but it happens.

I just got a PDA with the Nightforce Ballistics program in it (Exbal), trying to make it field practical for deals like this.

I agree with you, pull the trigger, keep good notes, learn from these situations and shoot better from the experience gained. We need good equipment, good marksmanship skills and knowledge to gain the confidence to shoot long. I expect that the second two are more important than gear when you consider the incredible shooting that has been done with marginal rifles and cartridges in the past.

 

[Michael Eichele]

I think Jerry hit the nail on the head. I have one barrel for my 300 RUM that by the time I get things perfected the barrel will be dead. I am having another barrel made for it, as identical as possible and hopefully at least I will know which bullets and powders it shines with! /ubbthreads/images/graemlins/grin.gif That way I dont have to spend near as much time burnig the bbl.