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Bullet flight path

 
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  #8  
Old 10-18-2004, 12:00 PM
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Re: Bullet flight path

Craig, your observations are indeed 'correct'. Programs make a lot of assumptions that unless adjusted for, will give erroneous results.

You have to adjust for humidity, temp, elevation, barometric pressure, true BC of bullet out of your rifle, true muzzle vel, accurate measured distance, etc.

If you ranged your distance with a laser rangefinder, your reading may be consistent but out. All rangefinders have a degree of error in their readings. So your 500yd reading, may actually be 485yds or something like that.

Your turrents may not be adjusting perfectly 1/4 MOA per click. If it were a bit off either way or changed slightly as you went up in rotations, you will get different results. As long as the results are consistent, the actual number really doesn't matter.

I use a Leica 800 to get my distances. Whether it is off or not, really doesn't matter. It is consistent. My drop table is based on one load, one scope and one rangefinder. Doesn't really matter if the true numbers are different from what I use.

I range a target, dial up, aim and shoot. A hit results. That is all I want from my gear.

Recent shooting with my 6.5-06 and 140gr SST highlights the problem with believing a program is absolute. With the adjustments I need and the muzzle vel of the bullets, the BC is seriously goofy as it comes from the program. The BC is high for sure, but over 0.8? Probably not.

However, the gear is consistent and repeatable which is what you need to have the confidence to shoot at LR.

Jerry
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  #9  
Old 10-18-2004, 12:23 PM
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Re: Bullet flight path

You have to adjust for humidity, temp, elevation, barometric pressure

Jerry, how do you get a local barometric reading you can count on?

...especially when you are out west hunting?
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  #10  
Old 10-18-2004, 12:57 PM
700 700 is offline
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Re: Bullet flight path

Len

I have heard good things about the equipment referenced here:-
http://www.ambientweather.com/ke40powestod.html

Link

Rgds

700
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  #11  
Old 10-18-2004, 02:06 PM
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Join Date: May 2003
Location: Wausau, WI
Posts: 47
Re: Bullet flight path

Jerry,

My rangefinder is a Lecia 1200. My scope is a Nikon 6.5 to 20 with 1/8 Min clicks. i do see your point about using one rifle one load and one rangefinder to eliminate any errors. I know that my MOA adjustments aren't perfect because I am using a 6" bull for zero. I figure if I can hit that consistently and those ranges I am good to go. Leaving this week for a elk hunt in MT. After reading several posts and seeing some of the drops it feels like bullets are crawling along [img]images/icons/shocked.gif[/img] I don't plan on shooting past 400 but I thought it would be good to 500 just in case...
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Old 10-18-2004, 02:49 PM
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Location: McKinney TX
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Re: Bullet flight path

Len,

I use the Krestel 4000 weather/wind meter. When I get off of the plane at the airport, I check with local weather or airport weather on the net and I adjust my krestel to match the BP. I work from there. It's not a perfect match, but as close to it as I can get.

I also don't fuss much with humidity. It has a very limited effect on a bullet, maybe 0.5 MOA at 1000 yards
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Mathew 5:16

Distance is not an issue, but the wind will make it interesting!
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  #13  
Old 10-18-2004, 03:02 PM
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Re: Bullet flight path

Len, this should get you the ballpark. http://www.theweathernetwork.com/wea...es/indexbc.htm

Just look up a city and it will show the barometric pressure usually from a local airport or environment station.

Not perfect but should be close enough for what we are doing.

Another option are the new generation GPS for mountaineering. They come with a climate mode which will measure pressures. How accurate? No clue. Comparing the two should get you in the right ballpark.

Craig, 200gr of really big bullet leaving at 3000fps is plenty big medicine for even the western kevlar skinned elk at ranges well beyond your comfort zone.

I would not hesitate to shoot one at up to 700 yds with my 6.5-06 and 140gr SST. On a broadside shot, I doubt I would find a bullet.

Your problem will be trying to hit the elk from field rests and naturally windy conditions. You bullet will certainly be lethal enough.

Nikon are very good mechanically but I would still do this torture test.

Go somewhere you can shoot rocks at ranges from 200 to 500yds. Just somewhere safe in the back 40. From the rests you plan on using, set up, range a rock about the size of the kill zone on your elk, dial up, shoot it. One shot one hit - yes or no. Reset scope to 100yd zero. Only take one shot per rock. No sighters at this range.

Let barrel cool, range another, dial up, etc. Keep repeating and you will quickly find how consistent you and your drop table are.

Now increase test by running the elevation knob through its entire range once or twice, then back to zero and dial up. Does it still hit where it is supposed to?

You will be amazed at the number of big dollar scopes that will fail this test. Their owner will claim that they need to dial past then back or only turn the knob slowly or only on Wednesdays after a full moon.

Hoogwash. I want my turrents to go to where I need right now. No mucking about and tweaking. In the field with your trophy deciding to leave the zip code, you need to know that I range, dial up, squeeze and start gutting.

Or else, get a whole bunch closer or get a better scope.

More practise. Stand up and move a round for a bit. Get back into field position, range another target, dial up, etc. Stand up, etc.

Keep repeating it until you gain the confidence to make that cold barrel shot hit. It is harder then it sounds. don't wait for calm days, in fact the worse the weather the better. You need to know what your load is likely to do in those Mountains.

Now increase the task. Go for a brisk walk or jog. Repeat the test and fire in under 10seconds. I think you see where this is going. Always start from your hunting zero on your turrent.

We all test our gear but do we ever test ourselves and that gear. I quickly found that scope eye relief was not right on one rifle, trigger weight not right on another, not field accurate enough for another.

All problems were eventually solved but they did not show up on the range. Test as you are going to hunt. That is the only way to know and for most of us, improve our confidence immensely.

My biggest problem now is finding them but that's another story...

Jerry
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  #14  
Old 10-18-2004, 07:06 PM
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Location: Wausau, WI
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Re: Bullet flight path

Jerry,

thanks for your input and explanations. Thanks to all for your help. Sounds like practice, practice and practice which is fun for me.
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