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7mm Berger 180 Hybrid twist rate help

 
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  #1  
Old 01-25-2011, 10:21 PM
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7mm Berger 180 Hybrid twist rate help

I just read an article on Litz's website about stabilization and twist rate for the 7mm VLD's. I have a 9.5 twist barrel that absolutly hates the 168's for some reason, but I don't want to give up on Bergers just yet. Anyways assuming that the 180 VLD and Hybrids need about the same twist, it appears that a 9.5 will have a chance at stabilizing this bullet. It might not be the best, but I'm gonna try the Hybrids before I give completely up on Berger.

Does anyone have any experience with this bullet (180 Hybrid) in something slower than the recommended 9 twist?

I'm at 1300 feet above sea level, won't be shooting below 32 degrees, and it'll be coming out of a 7 mag at about 2800 to 2850fps.

Thanks in advance.
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  #2  
Old 01-26-2011, 05:20 AM
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Location: Taranaki New Zealand
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Re: 7mm Berger 180 Hybrid twist rate help

I haven't used the Hybrid sorry but there is something I want to say as I believe twist rate is sometimes mis-understood.

The faster you drive a bullet, the less twist you need. Those 1-8 or 1-8.5 twist rate recomendations on the boxes of Sierra and on the Berger website are well suited to the 7mm-08 but not the magnums. A 1:9 twist is optimum for the current 180gr VLD in the magnums however Remington's Sendero 7mm Rem Mag, with its 1-9.25 twist shoots the 180 grain VLD very well. Sweets spots from the 26" barrel occur at around 2925 to 2950fps.

The trouble with the fast twist magnums we have, is that Berger have had to strengthen their projectiles to eliminate mid air bullet blow ups and other finnicky problems. The result, is that as time goes by, you will find the Berger less and less useful as a game bullet due to more frequent pin hole wounding. Berger perhaps could have done something towards studying the relevance of twist rate, versus the fact that hunters will mostly be using magnums rather than the smaller sevens typically seen in competition. Then again, its easy for me to pass judgement in hind sight, I have no idea what its like for them, the pressures they are under.

The twist rates some people use today are fast, the cartridges are getting faster, people are adding more grooves to their rifling, freebore is getting longer which is creating excessive yaw and the bullet makers are having to make bullets to handle all of these factors. The only way to make a true seperation between the VLD hunting bullet and the VLD target in the coming years, will be the addition of a polymer tip on the huting bullet to aid fragmentation. This will require a complete design change, a lot of money and a lot of time on the part of Berger.

I was quite saddened when I heard that Berger had made a .338 VLD capable of fragmentation on light to medium weight game, only to hear that the design was pulled due to incidence of mid air bullet blow up. The .338 bullet was then toughened up and re-released.

I have seen no reports from Berger as to the use of the new Hybrid as a hunting bullet. The word hunting simply doesn't appear anywhere. The only way we will know its merits, is to use it on game. It will most likely be very good on tough animals but on lighter bodied game, the 168 grain bullet might end up being the way to go due to better target resistance to initiate fragmentation. If the 180 grain is to be used on light game, it may have to be annealed as I have described here (hand loading):
https://secure.zeald.com/ballisticst...num?mv_pc=2984

Time will tell. I certainly don't envy Berger, it must be a difficult business. I am a great fan of their projectiles but I fear that such issues as fast twist rates versus magnum velocities is having or has the potential to have- a detrimental impact on their business.
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  #3  
Old 01-26-2011, 10:15 PM
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Re: 7mm Berger 180 Hybrid twist rate help

Thanks for the reply Kiwi.

I'm hoping that if these bullets can stabilize in a 7mm-08 going 2500ish fps that leaving my barrel at 2850 will make up for the difference in twist rate. I talked to the Techs at Berger today and was told the best thing would be to just try them and see what happens. Buying a box for 50 bucks to realize after the first 3 shots that they won't work will kinda suck, but I ordered some and will do some testing anyways.

I sure thought there would be more people that have tried this bullet in something other than 9 twist as a lot of the factory rifles offer 9.25 and 9.5 barrels.

Last edited by jsimonh; 01-26-2011 at 10:20 PM.
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  #4  
Old 01-26-2011, 10:42 PM
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Location: Taranaki New Zealand
Posts: 182
Re: 7mm Berger 180 Hybrid twist rate help

Before it slips my mind, here is a load from a recent client's Sendero:

Win Case
Federal 215 large magnum rifle primer
180gr Berger VLD seated to COAL of 86.8mm (bullet jump 1mm/40 thou)

ADI 2217 (H1000) powder.



Final load:

70.5 grains 2217/ H1000.

Velocity 2925fps.

Shot to shot max deviation 10fps.
Groups sub .25


Like I say, twist rate is 1:9.25. You'll need to check the reloading manuals before trying to duplicate the above as it will most likely be above maximum and your rifle may well have different bore tolerances. These loads were safe in this rifle, client has probably neck sized and reloaded the cases around 5 times by now.



Good luck with your tests.


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  #5  
Old 01-27-2011, 02:40 PM
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Location: The rifle range, or archery range or behind the computer in Alaska
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Re: 7mm Berger 180 Hybrid twist rate help

Quote:
Originally Posted by jsimonh View Post
I just read an article on Litz's website about stabilization and twist rate for the 7mm VLD's. I have a 9.5 twist barrel that absolutly hates the 168's for some reason, but I don't want to give up on Bergers just yet. Anyways assuming that the 180 VLD and Hybrids need about the same twist, it appears that a 9.5 will have a chance at stabilizing this bullet. It might not be the best, but I'm gonna try the Hybrids before I give completely up on Berger.

Does anyone have any experience with this bullet (180 Hybrid) in something slower than the recommended 9 twist?

I'm at 1300 feet above sea level, won't be shooting below 32 degrees, and it'll be coming out of a 7 mag at about 2800 to 2850fps.

Thanks in advance.
If you are happy with the overall features of the 168's, maybe try a different powder or two. Sometimes when a rifle 'hates' a given bullet it has more to do with the bullet/powder combo. Many times all you need is a different powder to make for a really sweet load even with a bullet you were convinced the rifle hated.

M
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  #6  
Old 01-27-2011, 08:30 PM
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Join Date: Jul 2010
Posts: 89
Re: 7mm Berger 180 Hybrid twist rate help

Quote:
Originally Posted by Michael Eichele View Post
If you are happy with the overall features of the 168's, maybe try a different powder or two. Sometimes when a rifle 'hates' a given bullet it has more to do with the bullet/powder combo. Many times all you need is a different powder to make for a really sweet load even with a bullet you were convinced the rifle hated.

M
If the Hybrid's don't work well, I'll probably give this a shot. Unfortunatly I don't have the money to just try multiple powders and I already have 8lbs of Retumbo. Eventually something will work out.
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  #7  
Old 01-28-2011, 07:23 AM
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Join Date: Sep 2008
Posts: 327
Re: 7mm Berger 180 Hybrid twist rate help

if you can find out/measure the bullet dimensions, you can work out the stability factor of the bullet from whatever barrel you have, here... JBM - Calculations - Drag/Twist
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