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 DESIGN FEATURES

QUESTION:
How did you arrive at the shape of your FN solid bullets? You must admit they look a bit strange.

ANSWER:
Handgun hunters have known from the time of Elmer Keith that you do not shoot animals with round nose bullets because they tend to run away, or even towards you, and that can be scary. That is why Keith developed the Keith type semi wad cutter. Our monometal solid is essentially a KTW for rifles. The massive flat front causes much greater deflection of tissue and the leading edge will cause cavitation in tissue that greatly increases penetration. The bullet is also less likely to turn inside the animal. We are currently the only manufacturer of a dangerous game solid bullet that combines a large meplat for cavitation and the HV concept in one product. We donít care what it looks like, as long it is the best bullet to get the job done. 

Note that penetration testing in media such as wood and sand shows less penetration than round nose solids due to the absence of fluids. See this article for more information on flat nosed bullets and how cavitation and shoulder stabilization works. The .50 calibre FN bullet at left below was recovered from the earth after fully penetrating a downed elephant. The illustration on the right is of  .458 caliber bullets recovered from a wood baffle box compared to an unfired bullet.

There is also the common misconception that an FN bullet will penetrate less than a round nose bullet.  Penetration is governed by the momentum driving the bullet forwards and the diameter and shape that causes drag and puts the brakes on penetration.  The higher the drag and the less the momentum is, the less the penetration would be.  

The drag caused by a cylinder shape with a flat, vertical front, is less than the drag caused by a round nose.  Drag is caused by the area exposed to the direction of travel.  The area of a round nose is larger than the area of cylinder shape.  When the nose on an FN bullet sets back, it becomes a cylinder and, should it set back further, so that the meplat becomes larger than the diameter of the bullet, the drag on the shaft of the bullet reduces.  The increased size of the meplat causes more drag but, overall, the drag reduces.  The proviso is that the shape that is presented to the direction of travel must be as close to a flat surface as possible to keep the square area to a minimum. 

QUESTION:
I understand you expect your HV bullets to reach more velocity at the same pressure than "normal" bullets. Why is this so? 

ANSWER:
The additional speed gained, is as a result of the coming together of a number of conditions.  We describe this fully in our load guide linked from the HV Bullets page. The basics of it is that the driving bands are much easier for the rifling to cut through, than the full engraving of the bullet bearing surface of a smooth bullet. The body of the bullet rides precisely in the bore of the rifle, while the driving bands are a perfect fit up to groove diameter of the rifling. 

The small amount of material that is displaced by the rifling, is largely pushed back into the space behind each driving band. The transition of bullet from case to fully in the bore, is therefore very fast and very smooth. With a full case of powder, slightly compressed, a magnum primer will pop the charge and bullet forwards far enough that, when the charge starts burning, the bullet is already in motion and partially inserted into the bore. In effect, a bigger case is created as the charge starts burning and, when case volume is increased for a given charge, pressure is lowered.

See this page where we demonstrated the ease of insertion into the bore by lightly lubricating an HV bullet, inserting it into the chamber of a loose barrel and tapping it all the way through the bore. The same stunt with a smooth or grooved bullet will result in a firmly plugged bore. With HV and FN bullets,  the ogive of the bullet is not engraved at all. This results in a major pressure reduction compared to smooth and grooved bullets where a part of the ogive has to be engraved before the bearing surface starts engraving

Pressure with HV Bullets therefore peaks later in the barrel, dissipating the heat in the pressure rise phase over a much greater surface area. Clearly, the temperature in the throat is greatly reduced as a result of the lower pressure. Our testing with a 220 Swift over a five year period and in excess of 2500 rounds fired at 4400 fps produced no throat erosion we could see. We have now rechambered this rifle to
22x64 in search of more speed and some indication of when to expect flame erosion with HV bullets.

QUESTION:
Why do some expanding copper bullets form petals when they expand and others not?  What impact speed is required to start expansion with GS Custom Bullets?

ANSWER:
HV bullets will expand fully at speeds as low as 1500 to 1800 fps. HP bullets are intended for shorter ranges mainly inside 350 metres and will expand fully from 1800 to 2000 fps. 

The forming of petals as the bullet expands is very important, even if they are torn off completely in the expansion process. We have found without fail that, if a copper bullet does not form petals and relies simply on a hollow cavity in the nose for expansion, it will deform asymmetrically and be much more prone to curving or deflecting  within the target.  It is also important that the nose of the bullet opens far enough to allow enough shortening of the bullet for better stability in tissue. This means a fairly deep hole should be present in the nose of the bullet. Ideally, the bullet should deform to either a fairly symmetrical mushroom or cylinder shape and at least to almost the same length as the bullet ogive.

.458" 450 gr HV bullet fired into water at 2500fps. Expanded diameter = 27mm (1.1")

If the bullet does not form petals or the cavity is too shallow, much energy is expended in the deformation and bending of the bullet . Such a bullet will also only show symmetrical deformation in testing media and if it strikes almost perfectly square on.

When the bullet is too long as well as asymmetrical after deforming, it will bend and tumble along a curved path through the animal. This explains why a bullet on a raking shot sometimes exits on the same side of the animal as the entrance hole. It is also the reason why a bullet does not hit the vitals inside the target and a good shot fails because the bullet does not go where it should.

With our HV and HP range, we spent more than a year on the cavity design to ensure the best possible deformed bullet shape. Even when raking shots are taken on game, HV bullets will afford you the best chance of reliable symmetrical deformation. This greatly increases the likelihood that you will hit the spot you were going for inside the target. 

Top Row: GS HV Bullets unfired and recovered from game.
Bottom Row:
Recovered GS HP Bullets. Three on the left from sand and three on the right from game. 


QUESTION:
How is it possible that a bullet that has mushroomed to double calibre leaves a smaller permanent cavity than a flat nosed bullet of the same calibre that clearly does not even expand?

ANSWER:
The question as you state it does not have all the facts. If the two bullets you describe have the same energy and momentum levels, the permanent wound channels will be similar in volume but differ in shape. An increase in speed brings new factors into play. 

If the bullet achieves a cylinder shape after impact, such as our HV bullet at high impact speeds, the temporary wound cavity volume is increased to such levels that the elasticity of the tissue is exceeded to a greater extent than with any other shape. The temporary wound channel then starts to contribute to the size of the permanent wound channel. This is because a cylinder is the most efficient shape for creating a large temporary cavity when it is driven at high speed. ("Bullet Penetration" by Duncan McPherson P57, P89, P277).  

In extreme cases the temporary cavity created by a cylinder shape will exceed the volume of the organ it strikes, or even the animal it strikes, and the body literally explodes as the elastic limits are exceeded. A graphic illustration of this factor at work is in the picture below. The rifle has started recoiling and the plastic water container at the right of the picture has been hit by a 130 gr HV bullet at 3000 fps. The bullet loses the petals as it penetrates the container, assumes a cylinder shape, and the resultant temporary cavity created by the cylinder shape, displaces water so violently inside the container, that the container bounces more than a meter straight up off the shelf. There is a slide show that goes into more detail about this here.
 

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GS Custom Bullets, situated in Port Elizabeth on the East Coast of South Africa, manufactures solid copper, turned, monolithic bullets for hunting and sport shooting. These bullets are used by hunters on several continents, hunting from the smallest of antelope to the largest of dangerous game, using the smooth HP bullet, as well as the more popular HV, FN and SP bullets with the patented drive band concept. GSC bullets are configured for the highest possible ballistic coefficients. SP bullets are mainly used for sport shooting. All GS Custom Bullets are coated.