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What keeps a round from holding MOA

 
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  #1  
Old 10-25-2004, 07:47 PM
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What keeps a round from holding MOA

I have several rifles that are good shooters. Sub MOA at 100, 200, about right on MOA at 300.
But by 400 they are way out.
I read about guys holding MOA at much longer ranges, is it because of barrel weight? Or some other shooting mystery?
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Old 10-26-2004, 07:38 PM
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Re: What keeps a round from holding MOA

This is usely due to the bullet shape and design it is how the bullet will react with the loss of rotation example a rifle with marginal twist rate will not be as stable at longer ranges.

I have loads that wont shoot worth a spit a 100 yards 1.5 MOA but group size at 200 may only be 2 inches and not much bigger at 300 2.5 to much spin.

Barrel weight will afect accurcy but a good shooting barrel of any weight will shoot good at any range
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Old 10-26-2004, 10:44 PM
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Re: What keeps a round from holding MOA

straydog,
It is no mystery it is probably a Tasco scope or 3x9 syndrome. get a good scope and use better bullets
B
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Old 10-27-2004, 09:34 AM
JBM JBM is offline
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Re: What keeps a round from holding MOA

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>This is usely due to the bullet shape and design it is how the bullet will react with the loss of rotation example a rifle with marginal twist rate will not be as stable at longer ranges.<HR></BLOCKQUOTE>

I'm curious to know why you say this. The forces acting to slow rotation are less than those trying to slow the bullet which means that the forces trying to overturn the bullet decrease faster as a bullet goes down range and therefore the bullet should get more stable (of course at the speed of sound, all bets are off).
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Old 10-27-2004, 12:25 PM
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Re: What keeps a round from holding MOA

Stray,

Accuracy is contributed to, or detracted from, by a whole host of issues.

Before you go off thinking that a rifle that shoots reasonably well at 100 yards falls apart at 400 because of a marginal twist rate, well - you'd better do some searching of the older posts on this site.

There's alot of wisdom that's been delivered over the last few years that you'd be better off gleaning from...
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Old 10-27-2004, 05:02 PM
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Re: What keeps a round from holding MOA

Straydog, assuming good quality bullets, I would steer you towards these areas: Velocity variations, shooting rests and technique, wind, and mirage.

It is not uncommon to see this type of situation. I can usually trace this back to poor powder burn/large vel. variations. Most commonly shown in ball powders especially older styles ie military surplus, and some extruded powders.

Used a ball powder in my hunting '06 that shot inside an inch at 200yds. Thought that would be great for LR. At 500yds, it wouldn't hit a 8X11 piece of paper.

Switching to a new type of consistently burning powder ie Hodgdon Extreme line or Reloader, problem goes away. I now use H4350 Extreme and get consistent sub MOA to as far as I want to shoot.

Are the groups stringing? If vertical stringing, then your load is probably at fault. If horizontally, it is probably the wind.

The further you shoot, the more important environmental conditions are. Mirage and wind can send you all over the map. Not easy to shoot MOA at LR even if your gun can.

If your load is stable and you are using quality bullets, once it gets to 300yds, it will continue to be accurate until it hits the ground. Bullets only show some dispersion when they go trans sonic (sometimes) which is a long ways from where you are.

How are your rests? Shooting technique? Try getting the most solid repeatable set up. A little variation like where you rest the rifle on the foreend from shot to shot, will make a big difference at long range. Rifle torque/roll during recoil can also 'throw' your shots off.

Good luck with developing this rifle. Shooting LR is not easy. That is why it is so addictive and fun.

Jerry
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Old 10-27-2004, 05:13 PM
LB LB is offline
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Re: What keeps a round from holding MOA

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>I have several rifles that are good shooters. Sub MOA at 100, 200, about right on MOA at 300.
But by 400 they are way out.
I read about guys holding MOA at much longer ranges, is it because of barrel weight? Or some other shooting mystery? <HR></BLOCKQUOTE>

In addition to what has already been said, I have two words: wind.

Good hunting. LB
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