Long Range Hunting Online Magazine Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker
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Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

#15
04-18-2009, 06:44 AM
 Platinum Member Join Date: Jun 2001 Location: Potomac River Posts: 5,088
Re: Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

Quote:
 So, if we have a 6.5/140/.287 SD bullet with the same SD as a 30/190/.286 SD bullet. Both will penetrate the same then according to Buffalobob. Since both have the same SD.
Two bullets with the same sectional density but different masses will not penetrate the same on an animal. One only needs to consider a 17 caliber bullet striking a shoulder bone versus a 338 caliber bullet striking a shoulder bone (both with the same sectional density) to understand that there needs to be consideration of the mass involved in the impact.

One can examine a theoretical rifle that would fire a quarter (25 cent piece) either flat surface forward or edge forward to visualize that with the flat surface forward the quarter has low sectional density and will make a big raised welt but little else. If the quarter is instead fired edge forward then it will have higher sectional density and penetration will occur. So we see that the with the same mass, but different sectional densities, the penetration will change.

The interplay of mass and sectional density is something we should consider when selecting a bullet for a particular application.
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#16
04-18-2009, 10:21 AM
 Silver Member Join Date: Jan 2006 Posts: 375
Re: Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

Quote:
 Originally Posted by Buffalobob Two bullets with the same sectional density but different masses will not penetrate the same on an animal. One only needs to consider a 17 caliber bullet striking a shoulder bone versus a 338 caliber bullet striking a shoulder bone (both with the same sectional density) to understand that there needs to be consideration of the mass involved in the impact. One can examine a theoretical rifle that would fire a quarter (25 cent piece) either flat surface forward or edge forward to visualize that with the flat surface forward the quarter has low sectional density and will make a big raised welt but little else. If the quarter is instead fired edge forward then it will have higher sectional density and penetration will occur. So we see that the with the same mass, but different sectional densities, the penetration will change. The interplay of mass and sectional density is something we should consider when selecting a bullet for a particular application.

I'll have to disagree to a point with this one.

I'll maintain that different caliber bullets of the same brand and construction with the same SD shooting at the same speed will penetrate the same. The larger caliber will have a larger cross section (CS) to slow it down once inside the animal.

Outside of comparing extreme caliber dia. A 6.5 130 AB will penetrate just as deep
as a 30 caliber 180 AB. CS can negate the advantage of weight. The initial hit on the
animal will be harder no doubt with the larger caliber.
#17
04-19-2009, 09:13 AM
 Bronze Member Join Date: Jan 2009 Location: Colorado Posts: 32
Re: Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

As a practical matter I chose the Berger 190 gr. VLD's for my .300 RUM, because I was able to load them in the magizine without using up space inside the cartridge. Thus far this load cleanly killed a 320 inch bull elk and 26 inch mule deer.

Yes the 210 grainers would be preferable but they are just enough longer, that they use up to much powder capacity when loaded from most magizines.

I have this combo loaded to 3390 fps using Retumbo, and have shot groups from the bench at 1000 yds. measuring under 8 inches, without any bullet failures. This was from a 1 in 12" barrel and it does work well in a 1 in 10".
#18
05-09-2009, 02:08 AM
 Junior Member Join Date: May 2009 Posts: 2
Re: Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

This is a an excellent site and my first post. I don't know why it took me so long to find it.So hello to everyone.

Would I be right in thinking that Eric's sweet spot method would apply to most other bullets?

Regards...

..Titan
#19
05-09-2009, 07:26 AM
 Official LRH Sponsor Join Date: Mar 2007 Posts: 634
Re: Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

Titan,
Hello and welcome to the site!

The 'sweet spot method' described in Eric's article will work best for bullets having secant ogives (meaning ogives profiled like the VLD) because they're the nose type that's most sensitive to seating depth. Other examples of secant ogives are: most of the Hornady Vmax and Amax bullets, the .30 cal 155 grain Lapua Scenar, and most of the JLK bullets.

Of course all bullets are sensitive to seating depth to some degree, but those having tangent ogives (nose meets bearing surface smoothly) are much less sensitive so the accuracy isn't related to seating depth as much as it is for secant ogives. Examples of tangent ogive bullets are: any Nosler bullet, most Sierra's, Berger's BT bullets, etc.

One commonly accepted reason for 'why' secant ogive bullets are more sensitive to seating depth is because that shape doesn't naturally self-center itself in the riflings as well as a tangent ogive, so it's more prone to tilting as it enters the riflings. As you probably know, a bullet tilting as it enters the riflings is bad for precision.

Hope this helps,
-Bryan
#20
05-09-2009, 08:36 AM
 Junior Member Join Date: May 2009 Posts: 2
Re: Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

Bryan

Thank you for your welcome and concise explanation.

Regards..

..Titan
#21
02-06-2010, 08:46 PM
 Platinum Member Join Date: Jan 2010 Location: Leominster mass, originally Salisbury Maryland Posts: 1,324
Re: Optimizing Precision And Accuracy From VLD Bullets By Eric Stecker

FIRST OF ALL i'D LIKE TO THANK ERIC AND BRYAN FOR ALL OF THEIR INPUT AND REPLIES TO QUESTIONS AND ISSUES. I AM PRESENTLY SHOOTING A SUPER ACCURATE 300 ULTRA MAG AND HAVE INTENTIONS OF USING YOUR 168 VLD HUNTING BULLET. AS I UNDERSTAND IT, MY RIFLE IS FREE BORED, JUST AS THE WEATHERBYS ARE. THAT BEING SAID, THE OGIVE OF THE BULLET IS QUITE FAR FROM THE RIFLINGS TO BEGIN WITH. I UNDERSTAND THE SWEET SPOT SETTINGS, AND UNDERSTAND THAT THIS IS A SECANT OGIVE. SO I GUESS THAT MY QUESTION IS, DO I START FROM MAX BOX LENGTH AND WORK BACK IN THE INTERVALS STATED IN THE OPTIMIZATION ARTICLE, OR DO YOU FEEL THAT MY OPTIMUM WILL BE AT MAX LENGTH. I HOPE THIS IS NOT A COMPLEX ISSUE TO CONSIDER. I'M SURE THAT MAX LENGTH WILL PROBABLY BE THE DEAL.

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