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Old April 25, 2006, 12:06 PM   #1
JD 500
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Why better groups @ 200 yds than 100 ?

Can anyone shed light on why I would be getting tighter groups at 200 yds than at 100 yds ?
I am relaoding 72.0 gr H4831sc into a .300 Win Mag. WLR primer and Nosler 180 gr ballistic tip.
(Out of a Browning BAR if it makes a difference.)

It certainly could be a fluke, but I did duplicate the tight groups twice at 200.

( About 1/2" to 3/4" at 200, and 2-3" at 100.)
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Old April 25, 2006, 01:02 PM   #2
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Fm

The Laws of Physics say......NO Way!
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Old April 25, 2006, 01:13 PM   #3
grizz007
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If I grouped less than a moa @ 100yds and it shoots tighter at 200yds I would wonder too . Maybe you ought to shoot at 300yds and see if your peculiar rifle shoots better there than at 200yds-if it does it is definately a keeper! You can quit your day job and improve your income by shooting. just having some fun. have a good day;.
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Old April 25, 2006, 01:15 PM   #4
Jim Watson
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Did you shoot at 100 or 200 first? The barrel might do better clean or fouled than the other way 'round.
Did you use the same bench setup and position?
Was it really truly the same ammo, preferably all loaded at the same time?

Two times could be a fluke, sub inch groups at 200 yards is outstanding for a sporting autorifle. How many shots?
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Old April 25, 2006, 01:46 PM   #5
NedreckSavant
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BEHOLD, THE MAGIC RIFLE! *bows down* The fouling might be the cause but that's still quite a difference. So yeah, what are things looking like at 300 yards? Let us know if you start putting things in the same hole...
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Old April 25, 2006, 03:26 PM   #6
jasonc84
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My guess is, that it takes a while to stabilize that bullet. The nosler ballistic tip is a long bullet and it takes a faster twist rate to stabilize longer bullets. So at 100 yards it hasn't stabilized completely and at 200 it has.
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Old April 25, 2006, 04:08 PM   #7
Mal H
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JD 500 - how many shots are in a "group"?

I'm sorry, but I just can't buy it. If you were to shoot a 2" group at 100 yds, there is no way those same bullets will come together at 200 yds to form a sub-inch group short of a tiny Kamikazi pilot on each bullet in conjunction with a once in every millenium favorable alignment of all the planets, sun and moon to assist him.

If a bullet isn't stabilized by 100 yards, there is nothing that is going to improve a group beyond that.

You need to do more testing, there's just something wrong there - somewhere.
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Old April 25, 2006, 04:09 PM   #8
JD 500
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1) Ammo all loaded at same time.
2) Shot the 100 yard groups before the 200 yd groups.
3) The rifle is usually, in my experience, more accurate clean.
4) all groups were 3 shot groups.
5) Going to try and confirm results at the range this weekend. And will also try 300 yds.

Maybe I will try 5 shot groups ??
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Old April 25, 2006, 04:11 PM   #9
JD 500
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Mal H,

I agree with you. Thus the post....
Someone on another forum suggested it could be a scope issue
Any thoughts ?

Any suggestion on testing procedures ??

Thanks

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Old April 25, 2006, 04:28 PM   #10
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I would say 3 shot groups are fine for your testing. But, no "fliers"! (Some folks will eliminate one or two shots from a group for some reason. Unless someone else accidently shot at your target, all shots count.)

Assuming you don't adjust the scope between the two distances (windage, elevation or power), I don't see how it can make that big of a difference, consistently. However, the reticle type might be a factor. What type does your scope have?

Do your testing on the same day at roughly the same time (same wind, temp, etc.)

Use the same cleaning procedure before or after each group. The idea is consistency in the testing. If you just run a wet patch followed by a dry patch, be sure to do the same for each group. If you do no cleaning, then do (don't?) do that for each group as well.

Try to use the same apparent size target. That is, if you use a 1" bull at 100 yds, use a 2" bull at 200 yds, etc. I think that is necessary to achieve the same sight picture since you aren't adjusting the scope power between the two distances.

Anyone else with suggestions?
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Old April 25, 2006, 04:40 PM   #11
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Mal, that tiny kamikaze pilot on each bullet is funny!hahahahahah

So long as trigger pull is the same-can only have that with a good trigger anyways. Might want to establish certain position in the rifle rest, shooting technique is invaluable-breathing as well. keep us informed.
good shootin
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Old April 25, 2006, 04:42 PM   #12
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My guess. Luck.
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Old April 25, 2006, 05:51 PM   #13
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Smaller groups at 200 than 100 moa wise is normal. Smaller group size makes me tend to think you have paralax problems at 100yd.
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Old April 25, 2006, 05:55 PM   #14
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2 sets of 3 shot groups amounts to six shots thats just not enough to know whats going on.try a ten shot group at 100yrds,, clean and then try a ten shot at 200 yrds.If your still seeing such a dramatic increase in accuracy over 100 yrds AND BACKWARDS ON TOP OF IT..I would say HOLY FU** AND Sit down to gather my thoughts(or whats left of them)..It just don't make sense.at least not that dramatic of a difference over such a short range.unless there could be some wierd bore issue or something.Or maybe we are in the twilight zone or something?
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Old April 25, 2006, 07:24 PM   #15
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Ammo Junkie - I'm not familliar with Parallax. I've heard the term, but thought it applied to much higher magnification scopes than my 3x9x40mm Bushnell Legend.

Most likely, I had the scope power set to 9 or close to it. Will this create a parallax problem at 100 yds ?

If so, what's the solution ?

Thanks, and Thanks to all who replied to my post.

And P.S. If it isn't the scope, I may have to go with Mal and Bender711's theories !!!!
( Do they have Kamikazees in Belgium ??? )
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Old April 25, 2006, 07:50 PM   #16
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People all say it can't happen...and on an actualy inch-measure baisis, I'd agree. On a MOA basis, have had it happen. 1.2" at 100 meters consistantly, but only 1.78" at twice the distance (200meters). this isn't some occasional BS group, this is the average of 5 -5shot groups per session, with multiple sessions.

First thought was a scope parallax problem...so I swtiched scopes (an old striaght 20X Leup.)with a rifle that has never shown this problem. Same deal.

(NEVER belive the little numbers on your objective...set the parallax by TEST not by just dialing the little number in).


So I thought it might be the order in which i shot them (usually shooting the 100 meter targets 1st, then setting up for 200meters). Nope.

(as much as we fight the idea, most of the rifle error ends up being biologic rather than mechanical)

Have read about other 6.5MM shooter (the rifle doing this was a 6.5RM built on a Ruger #3 action). "They" had several differnt takes onw hat caused this...and I only noticed it with the 140gr. Sierra BTHP's.

-----
Aside:
Never write off the old 160gr.RN Hornady's for accuracy. That same rifle was an honets ssub MOA rifle (using the same 5 -5-shot requirment)...and liked the 120's so well that I settled on them as my standard load.
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Old April 25, 2006, 07:53 PM   #17
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Jd,think of the target image in your scope like a front sight and the crosshairs like a back sight If you move your head around the image of the front sight sight moves in relationship to the rear. At different target distances the image of your target will be at slightly different depths. If the crosshairs are not in the exact same depth / focal plane any change in head position from shot to shot will cause changes in the relationship between the target image and cross hairs to change. It is like your are shooting with a slightly different zero each shot. If you scope has a paralax adj you can adj the paralax out at most any distance. If you don't have an adj, no big deal. You really don't need one much past 200yd any way. I am not an optical expert by any means, but If you want to know the baics of it, Ill be glad to tell you what little I know about adj and compensating at 100 if your scope has no adj.
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Old April 25, 2006, 09:50 PM   #18
JD 500
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Ammo Junky

Ill be glad to tell you what little I know about adj and compensating at 100 if your scope has no adj.


Yes, Please tell

Thanks

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Old April 25, 2006, 10:00 PM   #19
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The target itself can make a big difference too. If the target does not allow the same precision of aiming at 100 yards that it does at 200 yards it would only make sense that groups aimed with more precision would be tighter.

You will need to look for a target that works for your eye and your scope at each distance to make SURE you are getting a target that allows you to see every tiny little bit of aiming error.

I print the same target in different scales for different distances on my printer here at home. It takes a couple trips to the range to find just the right scale for the best precision but it is worth the effort.
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Old April 25, 2006, 10:40 PM   #20
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Concentration?
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Old April 25, 2006, 11:58 PM   #21
grizz007
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Denny,

Let me be the first to welcome you-Welcome. Hope you have enoyed this thread -I'm still befuddled. I still think he tried harder at 200 yds.
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Old April 26, 2006, 01:15 AM   #22
Bullet94
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"Hey guys! None of you argue with the well known fact that most VLD's shoot larger groups (MOA-wise) at 100 yards than they do at 300 yards and farther. Right?



Dan,

Wrong! I will argue with your statement above. It is myth not fact. I shoot many groups through two Oehler M43's with acoustic targets at 102 yards and 288 yards. (This system measures initial velocity twice, time of flight to 102 yards and 288 yards and determines the horizontal and vertical coordinates of each bullet at the acoustic target plane, saving all the data to a PC attached to each M43 system.). The groups are always larger moa' wise at 288 yards than 102 yards. Note that this is comparing the same group at two ranges, not two different groups one at 102 yards and one at 288 yards. And that is 1000 yard VLD bullets."



The above was taken from another forum but you might find it interesting.
Link to thread -

http://www.benchrest.com/forums/showthread.php?t=10744
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Old April 26, 2006, 02:00 AM   #23
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re the bullets are more stabilized at 200 than at 100, pure myth
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Old April 26, 2006, 06:48 AM   #24
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Never discount statistical factors.
Randomness is a given in nature and 2 3 shot groups does not a trend make.
Keep all the variables the same, ie, time of day, wind, barrel cleanliness,etc, etc., then shoot 12 to 15 5 shot groups at each distance and then lets see the statistical differences. I will be willing to bet that the groups open up at 200.
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Old April 26, 2006, 08:51 AM   #25
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gary - I don't think anyone was suggesting only a single 3-shot group at each distance. I suggested that 3-shot groups are fine for the purpose of disproving his initial findings, but with the emphasis on the plural "groups". Three groups at each distance should do it. I don't think the experiment is worth over $50 in .300 Win Mag ammo to conduct.
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