Re: Barnes X's actual BC?????

15 December 2003, 16:41

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I made a stop at Barnes factory this summer while in Utah. There are one or two full time employees and a vault full of rifles with pressure test barrels devoted to load development and bullet testing. They have a 200 (or was it 300?) yard underground range that they use for test firing with a Oehler setup to determine BC.

They also fire bullets at different velocities into a tank of water to determine expansion.

I was impressed, but that ain't hard.

Rick

I wish you're right

15 December 2003, 18:11

Gunnut 45/454

POP
Do you really think the Lawyers would let them put that in print if it wasn't true?

15 December 2003, 19:38

Jon A

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They may not meet their published BC, but neither do the Sierras, etc. I'm sure they drop a bunch after being battered in the magazine and the tips flattened.

I've tested Noslers and Sierras enough to have very high confidence in their published numbers. However, you do bring up a good point--I haven't tested any that could be/were damaged in the magazine.

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POP
Do you really think the Lawyers would let them put that in print if it wasn't true?

Are you kidding me? Ever watch TV late at night? Diet pills that will make you lose 50 lbs in a couple of weeks? A $19.95 gadget that will remove all unwanted body hair forever? An herb just as good as Viagra only it's cheap and you don't need a prescription? Do you think all advertising is accurate to within 10% of hard, provable numbers? If so, I've got a bridge in....Call Now and it's only $19.95!!!!

If Barnes actually tests their bullets for BC, that's great to hear. But they obviously aren't following the industry standard with what they do with that data. It is only raw data--it needs to be corrected to a standard.

I can put an engine on a dyno at sealevel in cold weather and make a bunch of power. I could advertise those numbers and sell it. When the customer puts it on a dyno next to other engines which should be less powerful and finds his engine is the one that has the least power, he might not be happy. What, I didn't lie! OK, so I didn't correct my numbers to the SAE standard that everybody else uses which mislead the customer. I didn't lie. I didn't even fib. While I what I did may have been dishonest and lousy, there's nothing illegal about it.

15 December 2003, 20:24

Jon A

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POP,

Since I mentioned that magazine article where the X's coefficients were tested I have been looking for it. I think it was on HA yesterday where it has been deleted.

They were much lower than what Barnes had published.

This is probably what you're talking about:

Remember, that's just raw data and not corrected for environmental conditions. But you can compare one bullet to another.

Accross the board, bullets with lower advertised BC's (sometimes much lower) beat the pants off the X's in side-by-side tests from the same rifle.

16 December 2003, 03:29

InfoSponge

Looks to me like, across the board, all of the tested BCs are much different than advertised. That makes me wonder whether there isn't some kind of systemic error in the data gathering, and makes me question just how accurately and precisely BCs can be measured with this setup. Strange looking raw numbers without an analysis of accuracy and precision aren't very useful.

16 December 2003, 04:51

Curly

POP, it really doesn't matter much whether it is .4 or .5 for hunting situations. I ran the numbers through a ballistics program and found the following: Assuming 2600 fps, the X bullet w/ the 0.5 BC and 270gr bullet: 3" high @ 100yd; 7" low at 300yd. The groove bullet would have the same vertical drop out to 300yd. W/ a 10mph cross wind at 300yd, the X bullet would be 7" off target and the Groove would be 8.5". At 400yd the X would be 12" off and the Groove 16".

With that said, I do think that the Groove bullet published BC is probably a little conservative or the X bullet is optimistic. But for hunting situations, it shouldn't matter since I doubt that you will be shooting a .375 at game over 300 yards. Where the BC really starts to matter is at ranges over 400 yards.

That Groove bullet does look more aerodynamic than the X. I guess the only way to really know would be to do a test like the one done where that table is shown with the various bullets tested in the .300WM above.

16 December 2003, 07:25

POP

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POP,

Since I mentioned that magazine article where the X's coefficients were tested I have been looking for it. I think it was on HA yesterday where it has been deleted.

They were much lower than what Barnes had published.

This is probably what you're talking about:

Remember, that's just raw data and not corrected for environmental conditions. But you can compare one bullet to another.

Accross the board, bullets with lower advertised BC's (sometimes much lower) beat the pants off the X's in side-by-side tests from the same rifle.

God Bless Jon! This pretty much mirrors all the BC #'s that I have ever seen being published by "independent" sources. Nobody even comes close to Barnes' claims. Hey do not get me wrong. My 378 loves the 270 XLC's! Check out the groups at 3120 fps.

When a rifle shoots the "almost perfect bullet" like this that is great news. I just wish the BC was up to par.

16 December 2003, 15:49

Jon A

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Strange looking raw numbers without an analysis of accuracy and precision aren't very useful.

Assuming the test was done correctly (bullets of each weight tested under the same conditions), the data are as useful as any you get from any scientific experiment. They're all going to have the same correction factor. If one bullet measures 20% higher than another under those conditions, it will be 20% higher after being corrected or measure 20% higher during "standard conditions."

For example, let's assume the advertised BC of .507 for the 180 Ballistic Tip is dead nuts on. That gives us a correction factor of 1.144. That would put the BC of the 180 X at .423 and the 180 XBT at .487.

16 December 2003, 16:02

InfoSponge

Assuming a constant scaling factor to account for the lack of accuracy is quite an assumption. Furthermore, it still doesn't tell you anything about the precision of the measurements, nor about any efforts to calibrate the data collection system, nor about the methodology used to estimate or correct for error. These numbers by themselves don't tell you a lot that is meaningful. Perhaps the original article does contain adequate additional information, I don't know. I do know that there are some decidedly funny numbers in that chart -- e.g., Barnes X and XLC bullets that should have the same BC but do not by a wide margin.

16 December 2003, 18:33

Jon A

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Assuming a constant scaling factor to account for the lack of accuracy is quite an assumption.

Are you implying that correcting for atmospheric conditions won't be a constant scaling factor for all the bullets (beyond very small variations)? If so, explain exactly how and please do show your work.

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These numbers by themselves don't tell you a lot that is meaningful.

Only if you assume Rick can't work the equipement properly. That's a pretty big assumption as well. Only if you ignore the fact that the rest of the bullets follow the pecking order of their advertised BC's rather closely except for the Barnes--they're the odd ones out. Only if you've never put the dimensions of these bullets into a computer program that will predict the BC and seen that these relative results come very close to how the computer predicts it should be.

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I do know that there are some decidedly funny numbers in that chart -- e.g., Barnes X and XLC bullets that should have the same BC but do not by a wide margin.

That's only one funny number for one weight. Catch any more?

I'll give you a hint. There's a missprint in the 180 data. the 180 X with a BC of .423 should have read 180 XLC. It's within 1% of the coated version as are the 150's and 165's. There's some validation for you right there. 10 shot strings for each bullet. In each weight, bullets which should be virtually the same measured within 1% of each other.

That's a pretty good precision check.

16 December 2003, 18:55

Jon A

[Edit] Damn, can't even fix a typo after 30 seconds or so?

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should have read 180 XBT.