What might be going on here?

11 March 2004, 04:22

.300 Win mag, 180 gr TBBC, 72.5 IMR 4350.

I can repeat the following results all of the time.

100 yds 5 shots 3/4 to 1 1/4 inches consistantly, center of group 2 inches high.

300 yds 5 shots 2 to 3 inches, 4 1/2 inches low.

BUT 200 yds all over the place generaly high and to the left.

Any ideas what is at work here

Dulcinea

11 March 2004, 04:53

OutlawMk26

what rifle, barrel, twist, velocity?
heavy copper in the barrel?
are the bullet holes round or oval?

sounds like a bullet stabilty problem. i would try a differnt bullet.
i use the same load with Nosler 180gr partion for all the big critters i hunt

11 March 2004, 05:21

ricciardelli

Scope parallax...

11 March 2004, 05:33

Dulcinea

Steve, How so with scope parralax?

Dulcinea

11 March 2004, 05:43

<eldeguello>

Quote:

what rifle, barrel, twist, velocity?

heavy copper in the barrel?

are the bullet holes round or oval?

sounds like a bullet stabilty problem. i would try a differnt bullet.

i use the same load with Nosler 180gr partion for all the big critters i hunt

IF the groups are acceptable (and yours ARE!!) at 100 and 300 yards, it is most certainly NOT a bullet stability problem! Bullets which become unstable and start top keyhole don't reacquire stability at greater distances.

It sounds like your problem is very unique; In fact, I have never heard of such a problem, let alone any explanation for it! IF you ever do find out the reason, please let us know about it!!

I guess scope parallax COULD explain this, but if this is present, it would be greater at either 100 or 300 yards, depending on how your scope is adjusted, than it would be at 200!

11 March 2004, 06:21

hivelosity

how much left at 200?
Are you shooting down hill@ 200?
is it a variable powered scope. It could be paraplex
how many click up at@ 200 @ 300?
Have you chronographed these loads @100 and @300.
they may be still climbing at 200 and be inconsistent load in that range????????????????????

11 March 2004, 07:19

Dulcinea

About 2 inches left and 3 inches high at 200 compared to 2 inches high at 12 oclock at 100 and 4.5 inches low at 12 at 300.

Everything darn near level, one thing I am looking at is I have been shooting in the pm and the sun does give me problems at 200yds. The gun is a Sako glass and pillar bedded. Leupold VXIII 3.5-10.

Just thought someone would recognize something simple here and appreciate all suggestions. I do not have a chrony so I am just estimating speed based on manuals.

I have only used TBBC's am gong to try Sierras to see what they do.

Dulcinea

11 March 2004, 08:10

CDH

OKay, the engineer in me os coming out. Watch out!

First rule of troubleshooting an intermittant problem is to find out what is changing. Obviously range, but what else? The problem doesn't remain at longer ranges, so we can eliminate bullet parameters.

Scope parallax could do it, if you are adjusting something for 200 yards (changing magnification or adjustable objectiove position can do it easily).

Shooter position can do it. Do you shoot from a differnet bench at 200 yards, and don't quite get your head in the same position on the stock? Some scopes shift point of aim if you change the angle (even slightly) that you are looking into it. Is the sun in your eyes is causing you to shift your sighting to reduce glare?

Is the 200 yard range shooting in a different direction, i.e. different wind? Moving 2 inches at 200 yards is easy with relatively light wind.

I am just shooting in the dark here, (pun intended!). Good luck!

11 March 2004, 08:12

hivelosity

is the target square to the bench? is it at an angle and leaning to you?
I have a 8x32 scope that I have to adjust up 15 clicks to be -O- @ 300yds the only way I can keep it at the same point of inpact each time i adjust i run up 30 clicks and back down 15.
If I dont the groups go high left for the first 2 rounds then they settle into a 3 shot group an inch or to lower.
hope some of this helps
shooting longe range can test every theory you ever had about shootin.

Dave

11 March 2004, 09:44

Jaywalker

Well, if you have a way to do it, you might try other intermediate distances, such as 150 and 250 yards, and see what the groups there do.

Theoretically, bullets don't fly in a straight line - they're corkscrewing down the path, converging and diverging from centerline. Certainly, a one-inch group at 100 yards does not mean two inches at 200 and three inches at 300. Your observations seem to suggest that soemthing else is at work, however.

Jaywalker

11 March 2004, 11:43

Dulcinea

OK, to sort through the suggestions. The 200 yd target is directly above the 100 yd target but you do get a bad glare in the pm from 200yd. The 300 yd target is a diifernt bench at a different location shooting at a different target butt.

I can try an intermediate range if no one else is on the range aT THE TIME.

The target is relatively square with the bench and is not leaning.
The gun was bought used in almost perfect condition but ended up with bedding issues, that was taken care of as soon as I found it. Scope brand new last year at this time so I do not have a history of having to change it.

It is starting to look like shooter error, and that is why I asked here to try to eliminate things.

Anybody else is welcome to whack away!!

It is not something that has shaken my confidence, hell I shot a bear and a deer with it last fall, just like a bug on the windshield a little distraction.

Dulcinea

11 March 2004, 18:27

hornetguy

...."Theoretically, bullets don't fly in a straight line - they're corkscrewing down the path, converging and diverging from centerline." ????????????????????

Now that's a totally new one on me.....
If I had to guess... I'd go along with the probability of parallax.... If your scope is set up to be parallax free at 100 yds, then you could be pretty irregular at 200.... in theory, it could be worse at 300, but maybe your technique is better when shooting at 300... maybe you are concentrating harder, forcing yourself to line up exactly the same way behind the rifle each time?
Line up your rifle on the target at 100 yds, bedding it securely in bags so it won't move. Then, while in shooting position, move your head slightly back and forth while looking thru the scope... if the crosshairs move across the target, then you have parallax problems. Do the same at 200 and at 300... somewhere in there you should be pretty much parallax free.... some scopes are set up to be free at 150.... sort of a compromise, I suppose.
Think about it.... if you can't place your head EXACTLY in the same position, left and right, up and down, behind the scope for each shot, then the crosshairs will be "off center", or, "out of parallax" for each shot. If you are leaning sort of consistently the same way when shooting at 200 yds, then your groups will be consistently off in that direction....
I can't explain the good groups at 300, unless you are just concentrating more, since the bull is "smaller" ???
just my 3 cents worth...