Increasing BC

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I dedicate this thread to future 6.5mm bullets with possible higher BC ratings.

...to start us off:

One method of increasing BC is the Base-bleed method used by artillery. I found a couple of references to tracer ammunition having increased BC due to the same effect.

From: http://www.globalsecurity.org/military/systems/munitions/base-bleed.htm
Conventional tracer bullets have reduced total drag by about 9.3 percent and base drag about 18.6 percent over comparable inert rounds, with attendant increases of velocity of about 4 percent, due to the rearward pressures exerted by the reaction gases formed during combustion of the tracer compositions.

I wonder if this company would be willing to do a 6.5mm bullet with the same design as their 5.56?
http://www.nationaldefensemagazine.org/issues/2002/Aug/US_Commandos.htm
We could then look at tracer burn time as well as increased BC (5.56 tracer is limited to about 300m and 7.62 to 600m - longer distances would be useful from an automatic weapon on a helicopter).

...to start us off: One method of increasing BC is the Base-bleed method used by artillery. I found a couple of references to tracer ammunition having increased BC due to the same effect....I wonder if this company would be willing to do a 6.5mm bullet with the same design as their 5.56? We could then look at tracer burn time as well as increased BC (5.56 tracer is limited to about 300m and 7.62 to 600m - longer distances would be useful from an automatic weapon on a helicopter).

Reginhild:

The problems with tracer is uneven burning of the tracer compound. Also, uneven loading of the compound in the manufacturing process. In other words, one side of the bullet may have more compound than the other side. Enough to make accuracy suffer if accuracy is what you are after. Tracers are longer bullets to hold the light weight of the tracer compound. You will find that the compound takes up most of the jacket if you ever dissect any tracers. They tend to break on the cannelure if they hit anything as the compound goes to the cannelure. When this happens, the remaining burning compound with that part of the jacket flies into the air and it appears that it is heading way, way, downrange when in fact it is only an optical illusion created from the compound burning out. I have shot tracers on KD ranges to see shot group sizes and changes in zero from the associated ball. Rather significant increase in shot group size and enough of a difference in elevation for me to question how well tracers hold the trajectory of the ball. I don't look at them as base bleed like artillery but they do the same thing -- reduce tail drag -- and this is probably necessary as tracers are long and are flat base.

I think that if you want something to give a higher BC than current designs, you will need a core that is denser than lead.

LR1955

Reginhild:

The problems with tracer is uneven burning of the tracer compound. Also, uneven loading of the compound in the manufacturing process. In other words, one side of the bullet may have more compound than the other side. Enough to make accuracy suffer if accuracy is what you are after. Tracers are longer bullets to hold the light weight of the tracer compound. You will find that the compound takes up most of the jacket if you ever dissect any tracers. They tend to break on the cannelure if they hit anything as the compound goes to the cannelure. When this happens, the remaining burning compound with that part of the jacket flies into the air and it appears that it is heading way, way, downrange when in fact it is only an optical illusion created from the compound burning out. I have shot tracers on KD ranges to see shot group sizes and changes in zero from the associated ball. Rather significant increase in shot group size and enough of a difference in elevation for me to question how well tracers hold the trajectory of the ball. I don't look at them as base bleed like artillery but they do the same thing -- reduce tail drag -- and this is probably necessary as tracers are long and are flat base.

I think that if you want something to give a higher BC than current designs, you will need a core that is denser than lead.

LR1955

Tungsten or depleted uranium, neither the two are going to be legal for us.

Joe

Check out the rebated boattail bullets from http://www.wildcatbullets.homestead.com/BulletTheory.html. He's a custom bullet manufacturer in Canada. He specialises in long, high BC bullets but he will make just about anything you want. Try a few, test them out, want a thicker or thinner jacket, just tell him. I believe all his jackets are a uniform thickness along thier length so expect the bonded bullets to perform like Interbonds with big mushrooms so if you want deep penetration go for the heavies. When I last talked to him he said he was soon going to be able to bond the 10 ogive J-4 jacket target bullets also, high BCs there.

Check out the rebated boattail bullets from http://www.wildcatbullets.homestead.com/BulletTheory.html. He's a custom bullet manufacturer in Canada. He specialises in long, high BC bullets but he will make just about anything you want. Try a few, test them out, want a thicker or thinner jacket, just tell him. I believe all his jackets are a uniform thickness along thier length so expect the bonded bullets to perform like Interbonds with big mushrooms so if you want deep penetration go for the heavies. When I last talked to him he said he was soon going to be able to bond the 10 ogive J-4 jacket target bullets also, high BCs there.

Bigfoot:

I am about to invest in some 6.5 dies myself. However I will probably stick with a 6 and 8 ogive as this will cover anything from 100 grains to about 140 grains.

I messed around with the 8's, 10's, and some ULD ogives for .30 caliber and they all needed relatively long jackets for me to get enough bearing surface for consistency. I tried making some lighter bullets that look identical to the one you posted -- long ogive and short jacket. They were real flaky due to a barely tolerable bearing surface.

About all I can say from my experiences in terms of making and shooting "VLD" designs is that I would more refer to them as "Lower Drag" than 'Very Low Drag". I made some 185 grain bullets using identical length jackets but with an 8, 10, and a "Ultra Low Drag" experimental ogive. I used the same load, primer, and brass with these bullets and shot them at 600 yards. Much to my surprise, I didn't record any significant difference in elevation. Maybe 1/2 minute. I did figure out that it is probably more important to have sufficient bearing surface than a real streamlined ogive. Oh yes, I close down my tips for the long range stuff and I believe that makes more of a difference in terms of drag than say the difference between an 8 or 10 ogive for example.

I do follow a principal that Berger uses. Bullet length is more important than bullet weight.

Good stuff and I wish that swager the best.

LR1955

Bigfoot:

I am about to invest in some 6.5 dies myself. However I will probably stick with a 6 and 8 ogive as this will cover anything from 100 grains to about 140 grains.

I messed around with the 8's, 10's, and some ULD ogives for .30 caliber and they all needed relatively long jackets for me to get enough bearing surface for consistency. I tried making some lighter bullets that look identical to the one you posted -- long ogive and short jacket. They were real flaky due to a barely tolerable bearing surface.

About all I can say from my experiences in terms of making and shooting "VLD" designs is that I would more refer to them as "Lower Drag" than 'Very Low Drag". I made some 185 grain bullets using identical length jackets but with an 8, 10, and a "Ultra Low Drag" experimental ogive. I used the same load, primer, and brass with these bullets and shot them at 600 yards. Much to my surprise, I didn't record any significant difference in elevation. Maybe 1/2 minute. I did figure out that it is probably more important to have sufficient bearing surface than a real streamlined ogive. Oh yes, I close down my tips for the long range stuff and I believe that makes more of a difference in terms of drag than say the difference between an 8 or 10 ogive for example.

I do follow a principal that Berger uses. Bullet length is more important than bullet weight.

Good stuff and I wish that swager the best.

LR1955


Richard, has many designs just never anything I'm interested in, in stock.


LR1955, who's making your dies..steel or carbide?

Richard, has many designs just never anything I'm interestedin, in stock. LR1955, who's making your dies..steel or carbide?

457:

I have Rich make my dies. I just tell him what I want and he makes them. If you want a peculiar ogive, he will make it although it may take some time. I have patience so will wait. I believe he uses carbide but like guys who make rifles for me, I don't care how they are made or how they work, only that they shoot well and are reliable.

BTW -- what are your recommendations for ogives for the 6.5?

LR1955

457:

I have Rich make my dies. I just tell him what I want and he makes them. If you want a peculiar ogive, he will make it although it may take some time. I have patience so will wait. I believe he uses carbide but like guys who make rifles for me, I don't care how they are made or how they work, only that they shoot well and are reliable.

BTW -- what are your recommendations for ogives for the 6.5?

LR1955


Game bullet:6S
Target:8-12S

One post said that tungsten cores would be illegal. I don't think so, ATK/Speer loads 500gr solids for the .458 Win Mag and .458 Lott with tungsten cores. Am I missing something here? Don

One post said that tungsten cores would be illegal. I don't think so, ATK/Speer loads 500gr solids for the .458 Win Mag and .458 Lott with tungsten cores. Am I missing something here? Don

Don:

Not sure what the laws are about armor piercing ammo but tungsten cores tend to be the ones used.

You may be missing the cost per bullet. He, he, he. Lead remains the cheapest and probably the best core material.

LR-1955

LR1955,

Did you ever get the bullet equipment you were talking about?

Rob

LR1955, Did you ever get the bullet equipment you were talking about? Rob

Reggi:

My dies will be here in the next ten days. I bought a couple of thousand J-4 jackets and are ready to go.

LR1955

One post said that tungsten cores would be illegal. I don't think so, ATK/Speer loads 500gr solids for the .458 Win Mag and .458 Lott with tungsten cores. Am I missing something here? Don



Solid tungsten cores as used by Armor piercing ammo would be illegal in Pistol calibers. Probably some of the more Hoplophobic areas in rifle calibers as well.

Using a compressed powdered tungsten core should not be, as it would more or less disintegrate on impact.