On several of the Scrapboard pages I've referred to APCR ammo. Since this type of round may not be as familiar to the reader as conventional AP ammo and more modern APDS and APFSDS rounds some word of explanation may be warranted.
During the Second World war increases in the armour protection of tanks led to a corresponding quest to increase the penetrative capabilities of anti-tank weapons. The most obvious way to do this was to increase the velocity of the projectile but above a certain level designers encountered problems. Above a certain impact velocity steel shot will simply shatter rather than penetrate. Tungsten Carbide seemed to offer a solution since it was harder and denser than steel but came with its own problems. Tungsten Carbide has nearly twice the density of steel so a round designed for a six-pounder gun may weight more than ten pounds. This would mean a lower muzzle velocity, longer flight time and more curved trajectory, greatly reducing the chances of the round killing a tank.
One solution to this problem was the APCR round or Armour Piercing Composite Rigid also known as HVAP (High Velocity AP) and APHC (AP hard core). APCR can be summed up as being an Armour Piercing Non-discarding Sabot round. A small core of Tungsten is surrounded by a sleeve or sabot of lighter material such as steel, alloy or aluminum. This sabot is fixed to the core and does not separate from it once the round leaves the muzzle. Some APCR rounds have unnecessary sections of the sleeve omitted around the waist of the round and the resulting shape results in some rounds being know by another alternate name of “Arrowhead Shot”. On impact with the target the surrounding sleeve tends to break up while the hard dense core punches through the armour. Generally the APCR round is made lighter than a conventional AP shot so it has a higher muzzle velocity.
The APCR combines a high muzzle velocity with a construction and materials that can put it to good effect so one might ask why APCR anti-tank rounds are seldom used nowadays. The answer is one of aerodynamics. While the core of the round is denser than steel the overall weight of the round is much lower than that of conventional steel shot of the same calibre. Lower sectional density means the round finds it harder to penetrate the air so it looses velocity at a greater rate. Beyond a certain range APCR rounds are less effective than conventional steel shot.
The solution to this was to have the sabot and the penetrating core part company once the projectile had left the muzzle and the sabot had done its job. With a high sectional density the main projectile has very good flight characteristics. This idea is of course the principle of the APDS and APFSDS ammo which has superseded APCR in the anti-tank role.
What interest does the Scrapboard have in APCR?
Certain parties are concerned about the capability of existing close-range weapons such as pistols and SMGs against body armour. One attempt to answer this problem are high velocity, very light, very small calibre rounds such a used by the FN P90 and HK P7. While these seem to be capable of penetrating soft body armour they make tiny ice-pick like wounds that are unlikely to have much immediate incapacitation effect –a serous liability for weapons touted as being for defensive purposes and for close combat.
Pistol calibre APCR ammo may offer a far more effective solution that still allows the use of existing 9mm and .45 weapons.
A round of this type appears to be in use in Russia and is known as the SJ-ESC or Semi-jacketed Exposed steel core. The French SFM PPI round used/uses a steel core in a brass sabot with three bourrelets, giving a lighter weight and reduced bore friction. The French Senix “High-Perf” had a steel core and tip surrounded by a thick plastic jacket. A .32 ACP High-Perf fired from a PPK could penetrate 24 layers of Kevlar! I believe there was also a round called the High-Perf intended for civilian use which had a lead outer; essentially a steel tipped hollow-point. The Saab-Bofors CBJ PDW uses a 9mm case necked down to 6.5mm and fires a round described as plastic surrounding a tungsten alloy core.
It is also possible that APCR pistol rounds would be cheaper to mass-produce than conventional AP rounds.
The weight of the APCR pistol round will be optimized to give adequate performance out to 50 metres. The APCR's tendency to loose energy more rapidly at longer ranges is not really a problem at normal pistol and SMG ranges.
APDS rounds could be produced for pistols but are more likely be harder and more expensive to produce and the sabot may cause problems when if suppressors are used. The APCR has another advantage over the APDS. Against an unarmoured target the round will still create a full calibre wound channel –it may be found that the sabot has mushrooming or fragmentation effects too.
By the Author of the Scrapboard :
Attack, Avoid, Survive: Essential Principles of Self Defence
Available in Handy A5 and US Trade Formats.