quote:

Originally posted by 308Sako:
The rifle should shoot better at 100!

Sierra's 80gr 223Rem bullet in my long range rifle was supposed to be likely to be "inaccurate" at close range. I can only say it was never as good as the 69gr. projectiles at 100yds, but I never had complaints for it from 300 to 900yards. (proves nothing , but I did have an adjustable objective scope on it.)

I see folks argue about this as well. The main thing that most do not consider when posting it can't be possible is that they are not taking into account that most who have seen it are shooting the heavy for caliber bullets that are not the norm for most shooters. Most folks gravitate towards optimum for caliber bullets and twist for caliber, (i.e.- 1-10 twist for .308 and 150 gr bullets)however when you go up to a 250gr bullet and go from a round nose or even a spitzer design to something in a VLD design your working on the ragged edge of stability. To make it even more exaggerated the same could be said about the .223 caliber bullets in the 70 - 90gr range which are heavy for caliber. Given most of these barrels are chambered in slower twist you get to a point where the actual stability of the bullets rotation is questionable. However this doesn't mean that it won't shoot accurately only that it might take longer for the bullet to actually stabilize or go to sleep and settle into the correct rotational spin.

I know that there are folks who want pictures and I had them, but after years of dust collection they finally went away. I purchased my daughter one of the Kimber sporterized 96's in 6.5x55 years ago. She wanted her own rifle and knowing her preferred style of hunting shots were not going to be much more than 200yds. When we got the rifle it would not shoot anything so we pretty much did an overhaul on it. New stock bedded action and new scope. While working loads up I found that the most accurate bullet was the then new Hornady A-max in 140grs. This bullet shot consistently less than 1" at 100yds. However, with it zeroed at +1.5" @ 100yds, it would shoot close to 4 o'clock at 150yds and around 8 at 200, then back up to almost dead POA on at 300yds. This was noted many times and had me questioning the barrel and the scope as well. I even asked a noted gunsmith about it at the range one evening and had this questioned theory explained to me. The groups were consistent at these ranges and the pattern so to speak was a tighter spiral as the distance increases. The totally disperse of the circle would generally be under 2" from 100 out, but still the group positions on the targets would reflect this as a spiraling effect which did get smaller as the bullet went the distance. The groups however would still keep to around 1" out to 300yds from a good rest and from the bench. So by all which has been reported the actual groups would be smaller by MOA at 300yds than at 100yds rather than graduating to larger spreads of 1 MOA per 100yds. WE have taken deer and feral hogs from up close to out past 350yds with this combo and never had anything but DRT results. Knowing that in hunting conditions one can rarely predict the exact tick one was aiming at in the first place and since the bullets would group into around 1†at all ranges with only a difference in where that group was, we didn’t worry about it too much, as it was all well within MOA of deer.

I would love to repeat the targets however since Hornady did a change on their A-Max a couple of years ago the newer ones do not shoot in that rifle anymore. Tried many things to get the groups back into just 2" but they simply do not work. Could be the rifle could be the barrel but I changed to the SST and it shoots wonderfully and doesn’t do what the original Amax did.

These are just my views on what all the arguing is about. All I can say is that some of the nay sayers get out with their standard twist rifles, and shoot some heavy for caliber bullets that are designed for just a bit quicker twist and see how they print. That particular rifle isn’t the only one I have seen this in. I have also seen similar results shooting heavy for caliber bullets from my standard .270 Win. The bullets are custom made 169.5 grs ULD VLD’s and just a tad under 1.5†in AOL and are designed for a faster than 1-10 twist. In my 1-8 twist .270 Allen Mag they shoot bug holes, however in the standard .270 they are a bit unstable until they get out a ways, and even then even though they will group somewhat the stability and velocity are not conducive for true accuracy. I would be more than happy to repeat this test if someone else is paying the tab on the bullets, shipping, and the cost to get me to my range and back. Just let me know.

quote:

It seems that some shooters believe in the theory that certain loads can actually defy the laws of physics and shoot much tighter groups at longer ranges(IE 1.5 MOA at 100 and .5MOA at longer ranges).

I think this is way overstating the phenomenon.

My rifle will shoot 5/8" to 3/4" inch groups at 100 yards. At 200 yards it shoots groups around 1" to 1 1/8. Not exactly what I expected but that is ok. Maybe I concentrate better at 200 yards.
Shoot 50 or a 100 different rifles 1000 rounds s each and you are bound to see something unusual now and then.

In the mean time Sierra has experience with this and will tell you that.

Thanks for your very interesting and informative post Mke / Tx.

So... not only can the groups get physically smaller down range but the spiralling bullet path can be consistent!

This could explain why my groups with 55gr bullets in my 1 in 16 twist hornet move around and change from vertical elongation to horizontal elongation then to angled elongation as the wind changes. (I thought it was just my loads or my rifle. One day, with a tail wind, I got a very neat vertical strung group with 60gr Nosler's. On the next occasion, with crosswinds, I got a narrow horizontal group - but the group had shifted into the wind! There are other explanations, I know).

quote:

Quoting ireload2

I called Sierra and talked to the ballistics technician named Paul Box. He said that long bullets such as the 6.5 142MK will not be settled down at the shorter ranges and will shoot smaller MOA at longer ranges. He said all of Sierra's QC testing was done with 10 shot groups at 200 yards except for military qualification testing which is done at 300 yards. If any one wants to dispute the issue they can call the bullet companies and report what you get back here.

quote:

Originally posted by David Antonucci:
My Kimber 8400 300wsm consistently shoots one inch groups at 100 yds and 1 inch groups at 200yds (1moa and .5moa). I'm not trying to start an argument, I'm just as confused as the rest of you

Following up on BigJakeJ1s suggestion of shooting through one target at 100 yards to another target at 300, would you be willing to try this experiment?

Adjust your scope such that at 100 yards the bullet hits several inches below line of sight. Put a target up at 300 yards strictly as an aiming point. Then put blank sheets of paper at 100 yards and at 300 yards centered on the bullets' flight path.

How do they group?

This experiment removes the variable of what your sight picture looks like at the two distances. (Eliminates the possibility that having the target closer makes your sighting sloppy) No fault attached, it might be subconscious, a muscle memory training issue, or perhaps optics.

This experiment assumes the first target does not disupt accuracy. If your normal 300 yard groups are maintained, that question is answered.

I love a puzzle

Larry (Lost Sheep)

quote:

Originally posted by ALF:
303 guy:

You should try some Advil for your headaches in the morning

So, how much powder you put behind your Advils and what kind of groups can you get with them?

Larry (Lost Sheep)

quote:

Originally posted by 303Guy:
[QUOTE] Fellas, you can actually watch the corkscrew through a good spotting scope when firing an S&W 29 with 240 gr bullets. I shot IHMSA for years and spotted for several friends using the S&W. These guns were very accurate shooting 1/2" groups at 50 yd's. But you can watch the bullet wind around the flight path and by 200 meters it is almost gone.

quote:

Bfrshooter: I agree with the bullet wobble....I have seen 44s and 45s do this on IMHSA courses while spotting for others...to me it seemed to be most noticeable about 90 -100 yards out and continued to impact at 200 meters...creating a pattern at best and misses at worst if the wind shifted slightly...

Interesting thought. It explains a lot of the objections, but not necessarily all.

My contribution to the thread is to suggest this would be easier to observe (and film, perhaps) if firing a flat-based (jacketed, of course) bullets early or late in the day with the sun at your back. The sunlight reflecting from the bulled bases (polish them before loading if you want) make the bullets as clearly visible as "tracer" rounds.

Larry (Lost Sheep)

Anybody near a range that is oriented East-West?

The whole issue of parallax being a factor is nonsense. We are talking about group size, not point of impact.

Parallax affects only the (group as a congregation) point of impact's relationship to the line of sight. No effect whatsoever on group size.

Consider the scope mounted in the bore axis. No parallax whatsoever. (Expensive to shoot, though and the Rangemaster will probably be all over you about the broken glass all over the range.)

Larry (Lost Sheep)

For your consideration:

Arrows do something like this. They have a spiral path that settles down to a central axis some distance from the bow.

When released (more so from fingers as opposed to a mechanical release) a slight sideward pressure on the nock causes the arrow to bend (or "bow") slightly and it "snakes" past the bow at the rest. This causes the flight path to deviate from the original axis of the arrow (as extended downrange). The fletching causes the arrow to spin, thus the direction of deviation rotates/revolves and the arrow takes a spiral path pretty much centered around the original axis of the arrow before launch. The size of the spiral shrinks down as the bowing of the arrow dampens out.

This is almost entirely aerodynamic forces, but some of the behaviour may be analagous to the forces on a bullet in flight?

Any thoughts?

Larry (Lost Sheep)

I love a puzzle.

quote:

Parallax affects only the (group as a congregation) point of impact's relationship to the line of sight. No effect whatsoever on group size.

Sheepy,
If your scope parallax is set wrong for the range it can make your group larger at one range than another if you don't change the parallax setting.
This causes you to make a wrong assumption about the source of the MOA variation.

After rereading your post I don't think you understand that in the context of this discussion, the scope's parallax SETTING is not the distance from the bore line it is a focal plane issue. You will have to check that out for yourself.

/

quote:

Originally posted by ireload2:

quote:

Parallax affects only the (group as a congregation) point of impact's relationship to the line of sight. No effect whatsoever on group size.

Sheepy,
If your scope parallax is set wrong for the range it can make your group larger at one range than another if you don't change the parallax setting.
This causes you to make a wrong assumption about the source of the MOA variation.

After rereading your post I don't think you understand that in the context of this discussion, the scope's parallax SETTING is not the distance from the bore line it is a focal plane issue. You will have to check that out for yourself.

ireload2,

Wow! I've never been called sheepy (or sheepish) before. If anything, I have been called a little too bold.

About the parallax, I have to stand (partially) corrected. Where I was talking about parallax between the scope's line of sight and the bore axis, this issue was parallax WITHIN the scope itself. Thanks for setting me straight.

As a surveyor, I knew about parallax in telescopic surveying instruments, but did not think about them within rofle scopes. Mea culpa.

As you suggested, I started my own research and immediately found these two sites:

<clip of wev site>

http://www.gameandfishmag.com/hunting/rabbits-hares-squ...unting/gf_aa106603a/

This is a condition that exists in all telescopic sights when the reticle crosshairs do not lie exactly on the image plane. All scopes have it, and much like the focus adjustment on a camera lens or binoculars, there is only one distance where it is "focused" precisely. Rimfire scopes are generally set for 50 yards, and big game scopes for 150. Scopes used for precision long range shooting normally feature an adjustable parallax to allow the shooter to set it to the appropriate range.

Excessive parallax makes the shooter's eye position very critical if repeatable accuracy is to be achieved. With a 150-yard parallax setting, big game scopes have excessive parallax at the under-50-yard ranges normally encountered by rimfire shooters. Because of that, the group size from those scopes may not be as good, or as consistent, as that produced by a lesser-priced rimfire scope.

The solution is to choose a quality rimfire scope, or send your big game scope back to the factory and request that the parallax be reset for 50 yards. It's not a complicated deal, but it can be the difference between sub-1/2-inch groups and 3/4-inch groups.

http://www.opticsplanet.com/msgboard/about6944.html

A scope that is parallax focused at 100 yards, will be free of parallax at 100 yards, regardless of the magnification. Even on a scope that is not parallax set for 100 yards, there is no parallax error if your eye is perfectly centered in the eyepiece...

<end clip of web site>

Parallax might be the cause of large groups at 100 yards if a scope is properly adjusted for 300 yards. The sight picture of the scope would be unreliable if the eye position behind the scope varied away from centerline. Thus the rifle would be difficult to aim reliably at 100 yards but very easy to aim reliably at 300.

However, the experiment I described in an earlier post would exclude that as a variable. The experiment had the shooter aiming at a 300 yard aiming point, but recording groups on a target at 100 yards AND 300 yards. The aiming point would, of course, have to be located so as not to be obscured by the nearer target.

Or maybe, the experiment could be run at night or on an overcast day, using a laser sight and a spotting scope instead of a scope as an aiming device. Eliminates the scope parallax issue entirely.

Anyhow, I have learned something new about rifle scopes. Thanks ireload2 and all contributors to this thread.

Larry (Lost Sheep)

This cracks me up....


Reloader