308 ammo, with a twist...

[CSM-H]

Hey to all, I am not up to speed on all the stuff you guys are doing but I read this on anothr thread and thought it might be interesting to read here, if not already discussd.  Forgive me if this is an old subject....  CSM-H

"Berger has designed and tested a new 308 bullet that will pass through the transonic zone without being upset. It is not yet listed on their website but is in the production line. Bryan Litz, the ballistician for Berger has loaded ammo listed for sale on his website. It may have some interesting applications for the military in terms of extending the range of the 308 sniper rifles".

Here is the link

http://www.appliedballisticsllc.com/Munitions/ABMTactical.html

**I think I fixed it. -Robocop1051

[unforgiven]

Don't know if it's me brother CSM-H but the link comes up error.

[Robocop1051]

This is direct from Berger's website:

VLD Bullet Design

The VLD (Very Low Drag) bullet design was born from a request made by the US 300 Meter Shooting Team.  It was determined that they were dropping points late in the matches due to recoil fatigue.  Bill Davis and Dr. Lou Palmisano were asked to design a bullet and case combination that shot flatter than the 308 case and 168 gr bullets the team was using at the time.  After a design was created Walt Berger was approached to make the bullet.  The 6mm 105 gr VLD was born and shot by the US 300 Meter Shooting Team using a 2” PPC (modified 220 Swift).  This combination shot with less felt recoil and a flatter trajectory than the 308 case using the 168 gr bullet and higher scores were the end result.  This successful bullet design soon found its way into all long range target competition and the VLD shape spread into all other calibers.

The VLD bullet design is a combination of two very specific features.  The first is a boat tail which is common on long and heavy bullets.   The second and most important design feature is the long secant ogive.  It is this ogive shape that allows the bullet to experience less drag as it flies to the target.  This reduced drag is how the VLD shoots flatter and is less affected by wind (less drift) than other bullets.  Reduced drag also translates into higher retained velocity.  These are important results if you want your bullet to help improve your accuracy by requiring less sight adjustments when conditions change.

For years we have relayed that it is best to jam the VLD into the lands for best performance.  This works for many rifles however there are many rifles that do not shoot the VLD well when the bullet is jammed.  We have learned that the VLD can shoot best as much as .150 jump off the rifling.  VLD bullets can be sensitive to seating depth and it has been found that these bullets shoot best in a COAL “sweet spot”.  This sweet spot is a COAL range that is usually .030 to .040 wide.

The quickest way to find this sweet spot is to load ammo at four different COAL.  Start with a COAL that allows the bullet to touch the rifling.  The next COAL needs to be .040 off the lands.  The third COAL needs to be .080 off the lands.  The last COAL needs to be .120 off the lands.  One of these COAL will outperform the other three by a considerable margin.  It has been reported that the VLD bullets don’t group as well at 100 yards but get better as the bullet “goes to sleep” at further ranges.  We have learned that by doing the four COAL test you will find a COAL where the VLD bullets will group well at 100 yards.  Once the COAL that shoots best is established you can tweak +/- .005 or .010 to increase precision or you can adjust powder charges and other load variables.  Frankly, those who do the four COAL test usually are happy with the results they get from this test alone. 

[CSM-H]

Sorry about the link it worked on the other site...thanks Robocop for squaring away the old guy..  :)    CSM-H

[edgecrusher]

*I think I fixed it* hahahahhahhahhaaa!      BOOM.  :'(

[unforgiven]

Got it thank you <thumbsup>

[unforgiven]

So from what I see that bulletis not for 1:10 barrel <dontknow>

[Robocop1051]

So from what I see that bulletis not for 1:10 barrel <dontknow>

On the contrary. The 1:10 twist should be better. They suggest a minimum 1:13 for the 175gr bullet. Normally the higher grain bullets appreciate the tighter twists. I think they are warning the long range guys with 1:14 twist barrels to shy away. There are some purists that shoot the 135gr bullets with a 1:14 barrel. These are mostly bolt rifle guys.

A 175gr bullet is not always used for 1000 yard shots due to the lack of muzzle velocity... This bullet appears to be contradictory to that school of thought.

[Jgun]

I just skimmed the article, but what I get when I read it is that it requires a minimum of 1 rev in 13" in order to stabilize the bullet, but that the reported results were obtained using a 20" Larue OBR with 1 rev in 11.25" twist. Unless i missed it being specifically stated that 1/10 is no good, My interpetation is that any barrel with a twist of less than 1 rev in 13" would not be ideal, but 1 rev in 10" is actually closer to 1.3 rev in 13".

[Robocop1051]

Edge has a 20" OBR, I volunteer him to buy this ammo and then find a 1,000 yard range to test it out for all of us <thumbsup>

[Jgun]

The Krieger I bought for my M1A build is 1/10. Many of those guys, that have shot these guns in hi power, have strong opinions about what works best in them. Krieger recommended the 1/11.25, but I chose the 1/10 based on the posts of some of the members. After ordering it I read that some prefer the 1/12 twist. I have been having second thoughts on my choice of 1/10. I'm hoping that I will not regret going with 1/10. This ammo sounds as though it might be just the thing for my configuration. Too bad I'm not going to be in a position to try it in that gun for several months, maybe I'll order some to try in my .308 AR's. of course all of them are 1/11.25 twist so it won't answer the question of how it performs out of a 1/10 barrel anyway.

[edgecrusher]

Edge has a 20" OBR, I volunteer him to buy this ammo and then find a 1,000 yard range to test it out for all of us <thumbsup>

<thumbsup> I'm in except: no 1000 ye range even close around here, and I can't mail order. Otherwise I green light this project!

Just for reference, I shoot 168gr gmm only out of my Larue so far, although I picked up a box of 175 gr gmm yesterday to try. When I ordered my Obr, Larue recommended 168 gr gmm

[Vlad308]

If no one gets to it Ill be back in the world in Aug. I MIGHT be able to talk a friend of mine into lending me use of some of her land for a test. It would be in a POF P308 w/ a 20" barrel machined at a 1:10 right hand twist.