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Old October 29, 2012, 06:06 PM   #1
FLChinook
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Disaster with Barnes TSX in 257 Weatherby

I tried the Barnes TSX 25 cal., 115 gr flat base, in my .257 Weatherby today. I also had a new Zeiss 4.5-14 50 scope with Leupold rings on my previously-installed Leupold one-piece base.

Powder was 63.5 gr of H1000 and brass was once-fired Weatherby (Norma).

I think the only variables were the new scope, new rings and Barnes bullets.

I sighted in using some year-old reloads made up of the same brass and 117 gr Sierra GameKing bullets (63 gr of H4831). Adjustments to the scope were exactly as expected (4 clicks = 1 inch in any direction at 100 yds). Finally, I shot two 3-short groups with the Sierras at 50 yards (point of impact .5" high)

Then I moved to the Barnes at 100 yards.

The first bullet missed the target entirely. I shifted back to 50 yards and more or less hit the bullseye. Back to 100 yards - another miss. I'm scratching my head in dismay.

Finally, I came back to 50 yards and shot 6 of the Barnes and got a spread from 4" at 7:30 to 2" at 10:30. Clearly, the shot at 7:30 would have missed the 100 yard target.

There was a guy shooting next to me who was a gunsmith and he very kindly took a look at the gun/scope. He could find nothing wrong. He suggested that since the Barnes are sold copper, maybe they have to make them slightly smaller (sold copper not being able to "squeeze" down a barrel as easily as a lead-based bullet).

I just miked the two bullets (Barnes and Sierra). The difference is not measurable by my non-digital mike and tired eyes but after setting the mike on the Sierra, the Barnes IS slightly smaller. Not enough for me to mike the difference but enough to feel a wiggle.

Does anyone have any idea what could be happening?

Thanks

Last edited by FLChinook; October 30, 2012 at 12:52 AM.
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Old October 29, 2012, 06:17 PM   #2
Brian Pfleuger
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Failure to stabilize is my first guess. What's your twist rate?
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Old October 29, 2012, 06:23 PM   #3
FLChinook
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Failure to stabilize is my first guess. What's your twist rate?
I measured the twist at 1/10"

One of the Barnes at 50-yds was keyholed...
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Old October 29, 2012, 06:38 PM   #4
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Failure to stabilize is my first guess
I would say so also. Solid copper bullets are lighter than lead bullets so they have to be longer to make weight.

Try some lighter weight jacketed bullets which would be quite a bit shorter and see if the problem goes away.

I wonder what the rifling twist in your barrel is also. It may be a 1 in 12 twist which would be for shorter bullets.
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Old October 29, 2012, 06:41 PM   #5
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Ah.
The keyholing is the key info. You're not stabilizing.
Don't worry about accuracy, continue to work up the charge until they stabilize, if they do, then worry about accuracy above that point.
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Old October 29, 2012, 07:34 PM   #6
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Your measurements were probably correct.

If you put a precision mic on the different bands and body segments of Barnes' solid copper bullets, you'll find that most are tapered or wasp-wasted (depending on the design).
I'd like to say it's so the bullets can handle the various bore dimensions seen in factory rifles, without causing excessive pressure in the tighter bores. .....but I don't really know if it's intentional, or just a byproduct (mild defect) of their manufacturing process.
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Old October 29, 2012, 07:59 PM   #7
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Don't worry about accuracy, continue to work up the charge until they stabilize, if they do, then worry about accuracy above that point.
I don't have the time nor inclination to try and sort out this problem. Just let me re-ask the question: Can failure to stabilize produce 12 moa patterns at 50 yards? That seems quite incredible

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Old October 29, 2012, 08:06 PM   #8
Brian Pfleuger
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It pretty well must have, since that what you were getting. What other explanation is there?

It shouldn't take any more time than any other load work up. Shoot your rounds. They'll either stabilize as you approach max or they won't. If they don't, you have an inaccurate load. If they do and you're happy with the accuracy, you're golden.
Should be just like any other load work up.
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Old October 29, 2012, 08:22 PM   #9
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I've always had good results with the Sierra GameKing 117 gr spitzer BT. Do you think Nosler's Ballistic Tip 115 would do as good or better?

What's your favorite powder for these two bullets?
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Old October 29, 2012, 09:48 PM   #10
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Can failure to stabilize produce 13 moa patterns at 50 yards? That seems quite incredible
Absolutely. If you are getting keyholes, the bullets are tumbling end over end in flight. Did you ever shoot pennies out of a slingshot? They curve all over the place. Similar effect when you have a tumbling bullet. I had some 45 Colt loads that were tumbling on me earlier this year. At 30 yds, I had bullets hitting 10 feet from each other. One bullet hit five feet to the right of my target, then another one hit a good five feet to the left. So when they are tumbling, there's no telling where they will go.

In my case, I tried a different powder and the problem went away. The tumblers shot perfectly fine out of a different gun however. It may not fix your problem, but it may not hurt to try a different powder.
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Old October 29, 2012, 10:10 PM   #11
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My .25-06 (Tikka T3) is a 1:10 as well. The 115 Barnes FBs are the most accurate bullet I've loaded. Sub MOA @ 100 yds. I can't imagine the 06 Remington can stabilize it but the weatherby can't. Maybe try H4831. That's what I use.
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Old October 29, 2012, 10:39 PM   #12
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Quote:
Originally Posted by FLChinook View Post
I measured the twist at 1/10"

One of the Barnes at 50-yds was keyholed...
Up the velocity or twist rate.

Sent from my PG86100 using Tapatalk 2
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Old October 29, 2012, 10:49 PM   #13
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Here's picture of the target. I initially thought there was only 1 keyhole but clearly all but maybe 2 are keyholed. My powder charge was at the suggested starting amount but the max is only 4 grains higher. Would such a small increase turn around this unbelievable effect?

This was at 50 yards...

257 Weatherby Barnes TSX Keyholes.jpeg
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Old October 29, 2012, 10:59 PM   #14
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Is the rifle a Weatherby?

If so, they have extreme freebore which will also help with low velocity with a starting load.

Get a chronograph and get them up to speed.
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Old October 29, 2012, 11:06 PM   #15
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My .25-06 (Tikka T3) is a 1:10 as well. The 115 Barnes FBs are the most accurate bullet I've loaded. Sub MOA @ 100 yds. I can't imagine the 06 Remington can stabilize it but the weatherby can't. Maybe try H4831. That's what I use.
I know a lot of people have great success with this bullet which is why I'm so surprised. H4831 and H1000 are both slow-burning powders and somewhat similar.

If increasing the velocity is the answer, then what will happen to the bullet downrange when the velocity reduces? Will it start out stable and keyhole at longer distances?

I am so tempted to abandon it altogether and go back to my GameKings or maybe try Nosler BTs...

My reloading books do not give me data on the Nosler
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Old October 29, 2012, 11:10 PM   #16
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Is the rifle a Weatherby?
Yes, it's a Mark V, one with a "blued" SS barrel that came from the Saco Maine plant in 1999.

I see some shooters at the range with chronographs but I would prefer not to have one... can't I rely on the reloading tables?
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Old October 29, 2012, 11:17 PM   #17
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Absolutely not. Without a chronograph, it is anybody's guess.

My best guess is with that huge freebore and minimum load, you are getting extremely low pressure and velocity, thus the keyholing and poor accuracy.
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Old October 29, 2012, 11:20 PM   #18
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Why don't I see this with other bullets?
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Old October 29, 2012, 11:37 PM   #19
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Why don't I see this with other bullets?
My guess is your particular problem is because lead free bullets are longer for their weight. They may be 115gr, but their length will be longer than a "normal" 115gr bullet, and contrary to what many think, its length, not weight which determines if a bullet will stabilize with a given twist rate.

I bet the 100gr TSX would shoot much better, as its length is more in line with what a 115gr conventional bullet would be....
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Old October 30, 2012, 12:24 AM   #20
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Is the tendency to keyhole a function of Ballistic Coefficient?

Here's the BCs:

Barnes TSX 100 .336
Barnes TSX 115 .335

Sierra GameKing 100 .355 (vel>2800)
Sierra GameKing 100 .310 (vel<1600)
Sierra GameKing 100 .333 (vel>between)

Sierra GameKing 117 .410 (vel>2500)
Sierra GameKing 117 .403 (vel>1800)
Sierra GameKing 117 .370 (vel>between)

Nosler Ballistic Tip 100 .393
Nosler Ballistic Tip 115 .453

Nosler Partition 100 .377
Nosler Partition 115 .389
Nosler Partition 120 .391

Berger VLD Hunting 115 .466

It's interesting that the Barnes TSX bullets of different weights have almost the same BC. Every other bullet I've checked has a larger BC for increasing bullet weight.

The Nosler Ballistic Tip seems to have a better BC than the Partition; almost as good as the Berger...

I don't think Bergers would work will with my gun (if it has "huge freebore") as Berger recommends lengthening a round to where the bullet almost touches the lands. That would be hard to do in my case.

It's interesting that Sierra gives different BC values for different velocities; slower is not better

Last edited by FLChinook; October 30, 2012 at 12:57 AM.
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Old October 30, 2012, 01:50 AM   #21
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In your photo, I don't see anything truly key-holing, but they may be yawing (still a stability issue).


Don't worry about the ballistic coefficients. They have far more to do with a bullet's flight characteristics, than stability. And, a bullet's shape affects the BC more than length alone.


Unrelated to the OP, but related to your last post....
Note how Sierra quotes multiple BCs for their bullets.
That's because G1 ballistic coefficients actually change significantly in flight (as velocity changes). And, the standard G1 model doesn't apply well to modern boat tail designs.

Because of this, manufacturers have to decide what BC to use. Some use the highest BC the bullet is likely to achieve. And, some are more conservative and use an average of the expected velocities to get their BC.
Without knowing what velocity is used to calculate the listed BC from any given company, comparing G1 BCs of different bullets really doesn't do much good unless they're significantly different (like a .273 vs a .426).

Most precision bullet makers will also list the G7 BCs for their bullets. The G7 model is much better suited to modern boat tail bullet designs, and allows for more precise ballistics calculations. But... G7 BCs are much lower for any given bullet, than the same bullet's G1 BC. So, "main stream" manufacturers are hesitant to start listing G7 BCs for their bullets. They don't want people getting confused and thinking the lower G7 BC is representative of the older standard of the G1 BCs.
Here's an article, if you want more information. (It also has representations of the G1 and G7 standard projectiles.)
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Old October 30, 2012, 02:12 AM   #22
FLChinook
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Don't worry about the ballistic coefficients. They have far more to do with a bullet's flight characteristics, than stability.
Sorry to belabor this, but if bullet stability is not a function of BC, what is it a function of? Is there some minimum muzzle velocity for any given bullet and barrel length/twist? Are we "doomed" to learn about each bullet's stability with each gun by trial and error; hopefully not...

Thanks for the useful presentation of BC data. I knew Berger gave G7-BCs but I've not been able to make comparative use of it (other than between Berger bullets) as no other bullet manufacturers give the same data.
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Old October 30, 2012, 03:26 AM   #23
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Ballistic Coefficients are a numerical representation of how closely a projectile's in-flight performance conforms to that of the "standard projectile". So, as mentioned earlier, that's generally the G1 standard projectile.

A Ballistic Coefficient represent a bullet's resistance to aerodynamic drag.
Having an approximation of that factor allows one to calculate fairly precise trajectories for a given velocity.

That's pretty much it. BCs just tell you how well the bullet will resist aerodynamic drag, in relation to the "standard projectile".


When we're talking about stability, we're referring to rotational stability: A bullet rotating in a manner that is stable and predictable, around its long axis.
A rotational velocity that is too low may not keep the bullet stable on that axis; and a rotational velocity that is too high can magnify small balance imperfections in the bullet, causing it to also be unstable.
(If you rotate them really fast (like 350,000 rpm), they can self-destruct before they reach the target.)

By saying your rifle is not stabilizing the Barnes 115 gr TSX, we're referring to them having a low rotational velocity. They just aren't spinning fast enough to remain stable in flight. To fix that, you must increase velocity, or the barrel twist rate. Since replacing your barrel probably isn't on your to-do list, increasing the powder charge for more velocity is the better solution (if you can do so).

If you can't find a powder that will get you enough velocity to stabilize that bullet in your rifle, you have two choices: 1. Forget about that bullet. 2. Rebarrel the rifle with a faster twist rate.
(I would opt for #1.)


If I was in your position, I would:
Give away the rest of the bullets, if it was a box of 50.
Increase the load, to try to make these work, if you bought 100 or more.
And use the 80 gr TTSX (or 100 gr TSX - the heaviest I would go) if you want to try a different Barnes bullet.
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Old October 30, 2012, 09:34 AM   #24
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Barnes manual loading data for their 115gr TSX in a 257 Wby start load is 66gr/H-1000 @3073fps and max load of 72gr/H-1000 @ 3287fps.

If you look at Hodgdon data they list the Barnes 115gr XFB start load of 67gr/H-1000 and max of 71gr/H-1000 both list the Fed 215 primer.

you already had this post from

mrawesome22 Absolutely not. Without a chronograph, it is anybody's guess.

My best guess is with that huge freebore and minimum load, you are getting extremely low pressure and velocity, thus the keyholing and poor accuracy.
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Old October 30, 2012, 09:54 AM   #25
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Barnes manual loading data for their 115gr TSX in a 257 Wby start load is 66gr/H-1000 @3073fps and max load of 72gr/H-1000 @ 3287fps.
I took the following from the Barnes website for this bullet and H1000: Starting Load 63.5 (3101) and Max Load 67.5 (3243). That's quite different from 66/72. I would think boosting the load from 63.5 to 72 (13%) might give enough of a velocity increase to stabilize the bullet. nmbrinkman says his Tikka T3 does very well with this bullet using H4831. He doesn't say what his load is (min or max) but I believe H1000 has about the same burn rate as H4831.

It's pretty clear now that this bullet needs more "umph" for my barrel. I would never have thought that different barrels for the same caliber would have different "umph" requirements but I guess they do.

I think, as in the old closing of Dragnet, "This case (on this bullet in my barrel) is closed"!

I just wish we could establish some direction as to which bullet shape might be most likely to be better stabilized in my barrel without needing max loads.

Thanks everyone.
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