Berger FB HBC
- Thread starter sbindy
- Start date
OK, from the Berger Bullets Quick Reference Sheet, the 69 grain does in fact have a 15-caliber ogive. If it is a secant ogive, it is the front part of a VLD bullet. Also from the data sheet is a calculated B.C. which is .308.I would like some feedback from the forum on the Berger High BC FB bullets in 6mm. Particularly the 69gr bullet. To the best of my knowledge these are a VLD bullet without the boattail. Are they superior in windy conditions? Any help is appreciated.
In contrast, the 66-grain Berger bullet with a 7.5 caliber ogive (quite conventional) has a calculated B.C. of .269. That is some, but not a hell of a lot of difference.
Many long-range shooters will tell you that variance in B.C., when it occurs, is a big problem. A 0.020 variance in B.C. is worth about 4 inches at 1,000 yards, and is significant at 200 and 300 yards with the types of aggs we shoot in point-blank BR. Back when Larry Bartholomew did some testing with an Oehler 43, he found that .020 variance in B.C. with VLD bullets -- though those did have a boattail.
Many of us long-range shooters believe, with some evidence, that is is just flat harder to manufacture a consistent 15-caliber secant ogive bullet.
Erick Stecker of Berger sort of counters with the statement that it is just harder to tune them. Moreover, the tests that Bartholomew & Tooley did were were several years ago, and Eric also states that Berger is getting much better at the manufacturing consistency of their VLD bullets.
Consistency matters. Some of us -- I'd think many of us -- will stick with a proven bullet & powder combination at the expense of a barrel. It might be true that a particular barrel that wont agg with our chosen components would agg with other components. But the time & cost of figuring that all out, and the relatively short accuracy life of a barrel means we don't try; we stick with what works & fit another barrel. That is how benchrest shooters -- some of us anyway -- address the problem.
Finally, I'd like to point out that you have to be able to read the wind. It doesn't mater so much what the absolute wind drift is; more important is that you know how much to hold off with your chosen components.
So there is no answer to your question. If you want to give them a try, by all means do so. All I'm really trying to point out is that benchrest shooters do know all this stuff, and have found consistency paramount in maintaining small aggregates, which is what wins matches.
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Eric Stecker
New member
68 gr is a 12" twist
Yes.
I agree with much of what Charles posted. One exception is that the 66gr High BCFB which has been discontinued was a 15 cal secant (not a 7.5) just like the 69 gr and 88 gr High BCFB.
Regards,
Eric
Yes.
I agree with much of what Charles posted. One exception is that the 66gr High BCFB which has been discontinued was a 15 cal secant (not a 7.5) just like the 69 gr and 88 gr High BCFB.
Regards,
Eric
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Yes, I should have said the 65 grain has the 7.5 tangent ogive.
I'm not sure what you are asking. That the 69-grain High BCFB bullets are a little longer, & therefore require a slightly faster twist for stabilization, doesn't affect what I said about the accuracy capabilities of the two bullets.
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sbindy
Steve B
I guess I should have clarified my question a little better. What I was asking was if I bought a 1-12 twist barrel that is recommended for the 69gr bullet and didnt have good luck with it, would I still be able to get acceptable results from the 68gr FB bullets in a barrel with that twist rate. From what I gather most shooters use a 1-14, and I didnt want to get tied up into something that would be a total waste of time because of a small change like that. Thanks for your help.
LARRY FEUSSE
New member
I have tried these bullets also and find that they may need special considerations in order to work properly. First, my rifling twist calculator confirms Bergers recomendation of a 12 twist for these bullets. The twist could be streatched upward to about 12.7 if temperatures are warm (70 and up) and if velocities are kept up (3250 or more). Also, note that some barrels differ slightly in their advertised twist. A cut rifled barrel such as Krieger or Bartlein will be quite exact, but a button rifled barrel may vary as much as a half inch of twist (an advertised 14 could actually be 14.4, 14.5, 13.6, etc.).
Another thing about this bullet is that it has a relatively short bearing surface and a long point area ahead of the bearing surface. It is made on the .900 in. long jacket, where as the standard 68 grain bullets with about an 8 ogive are usually made on a .825 length jacket. This is why the faster twist is needed, to stabilize the longer and comparatively lighter bullet.
I have found that these longer bullets with the short bearing surface may also be more sensitive to loaded round straightness. It may be good to check and adjust the straightness of the loaded rounds if satisfactory results are inconsistant.
Hope this is helpful.
Larry
Another thing about this bullet is that it has a relatively short bearing surface and a long point area ahead of the bearing surface. It is made on the .900 in. long jacket, where as the standard 68 grain bullets with about an 8 ogive are usually made on a .825 length jacket. This is why the faster twist is needed, to stabilize the longer and comparatively lighter bullet.
I have found that these longer bullets with the short bearing surface may also be more sensitive to loaded round straightness. It may be good to check and adjust the straightness of the loaded rounds if satisfactory results are inconsistant.
Hope this is helpful.
Larry
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