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Target Knobs vs Clicks vs Alt. vs Temp

 
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  #1  
Old 10-19-2005, 08:56 AM
 
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Target Knobs vs Clicks vs Alt. vs Temp

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
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  #2  
Old 10-19-2005, 10:24 AM
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Join Date: Sep 2002
Location: colorado
Posts: 878
Re: Target Knobs vs Clicks vs Alt. vs Temp

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
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  #3  
Old 10-19-2005, 11:20 AM
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Location: tennessee
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Re: Target Knobs vs Clicks vs Alt. vs Temp

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.
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Old 10-19-2005, 11:57 AM
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Re: Target Knobs vs Clicks vs Alt. vs Temp

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"? [img]/ubbthreads/images/graemlins/grin.gif[/img]

When my "dope" goes to hell in a handbasket it's usually because of mirage rather than elevation.
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  #5  
Old 10-19-2005, 12:38 PM
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Join Date: Jul 2001
Posts: 1,459
Re: Target Knobs vs Clicks vs Alt. vs Temp

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
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  #6  
Old 10-19-2005, 03:31 PM
 
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Re: Target Knobs vs Clicks vs Alt. vs Temp

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...
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  #7  
Old 10-19-2005, 05:15 PM
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Re: Target Knobs vs Clicks vs Alt. vs Temp

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!
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