Since I broached the topic of metal-piercing projectiles yesterday with the KTW, here are a couple of French metal-piercing rounds from the 1970s and 1980s.

The Arcane was the brainchild of Fabrice Bodet. He filed his first patent application in France in June 1978, and received patent FR2429407B1 in December 1980. Bodet did not get around to filing a US patent application until May 1985, which received US Patent #4,819,563 in April 1989.

https://patents.google.com/patent/US4819563A

Bodet lathe turned copper projectiles with a conical ogive. The US patent mentioned a preferred angle of 60-degrees, but this varied in practice due to caliber and cartridge over-all length. He also mentioned using a thin film coating of silicone. Bodet never found a manufacturer for complete ammo, but turned out many projectiles as well as loaded experimental rounds. The latter were typically overloaded as Bodet had no experience in manufacturing ammunition. He was basically using whatever propellants were available to him in France. Chamber pressure was reported as follows: 9x19mm – 45,000
PSI; .38 Special – 50,000 PSI; and .357 Magnum – 54,000 psi!

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THV (Très Haute Vitesse/Very High Velocity) was developed by Robert Antoine and Jacques Laurin. Antoine and Laurin filed their first patent application in France in September 1981, and received patent FR2513369B1 in February 1984.

Unlike the Arcane, ammunition manufacturer SFM (Société Française de Munitions) quickly acquired the patent rights and began manufacture of the THV. SFM filed a US patent application in November 1984, and received US Patent #4,572,077 in February 1986.

https://patents.google.com/patent/US4572077

The THV was machined from brass, and used a concave ogive that converged to a center post. The base of the projectile was hollow to reduce weight and to allow for the use of more propellant in the loaded cartridge. The concave ogive would supposedly give a snowplow effect on soft-tissue, while the center post aided with penetration against hard cover.