I remember reading about this type of bullet, made in Europe, in the late 1960s. I believe it was prior to 1969, but I cannot be sure. The information appeared in an article in one of the popular gun magazines of the day - probably Guns & Ammo - since that is what I read most in those days.
The bullets were the same conical shape with no curve to the taper between shank and meplat. They were solid bronze and turned on a screw machine. My memory says they were made in France by a company (or marketed by a firm) called “Mystere” or something very similar. They were being advertised on the U. S. market in caliber .38 Special or .357 Magnum. I believe there was a 9x19mm loading and a .45 ACP loading as well. They were sold only as loaded ammunition, I think; but I seen to recall a possibility of being imported as components as well.
Being bronze, they were relatively light weight. They were advertised has having very high velocities. (This was before Lee Juras and Super-Vel, if my memory serves.) It turns out they were loaded to European pressure levels and the .38 Special loading was right at the maximum for the U. S. (SAAMI) pressure levels for .357 Magnum. So that didn’t help their sales much.
They were not imported in any quantity to my knowledge. Then again, at that time I was a dirt poor young fellow about to enlist in the Marine Corps and certainly didn’t have any spare money for ‘exotic’ ammunition. (I could barely afford to buy surplus hardball for my surplus Ithaca 1911A1.) Nor do I remember seeing them offered in any of the gun shops I frequented then.
From what I know now, the French national police (I can never remember the exact title correctly) was still carrying a sidearm in .32 ACP. So it is quite possible that cartridge was part of the bronze bullet - high velocity experiment. That is a conjecture on my part.
The final nail in the coffin came later. The mainstream media were beating the drum about ‘cop killer bullets’ which would defeat ballistic vests. Those bronze bullet rounds would defeat the vests of that day and probably now. Not so long after that, the Leftists in the U. S. Congress caught the panic from the ‘media’ and importation of ‘cop killer bullets’ were banned quicker than one could say ‘politically correct’. Domestic manufacture was prohibited later.
Similar but not the same. When I was a humble but lovable Border Patrol Agent I purchased a box of Winchester Super X metal piercing .357 Magnum ammunition. I carried them in my duty bag for a number of years should I need to shoot up a vehicle. (There was no policy at the time regarding shooting at vehicles; for the tally book, the event never presented.) The bullets were similarly shaped, but according to the advertising, they were lead cored and fully jacketed with an extra heavy material. No mystery about those.