Here is the information and pictures kindly provided by John. Thanks a lot, my friend!
"1 - The picture shows, left to right, the well-known DDR (East German) .22 LR caliber adaptor, which is made of steel. The picture shows it with a .22 cartridge in the adaptor, with the “bump” at the nose being the tip of the lead .22 bullet protruding from the cartridge. The OAL of this cartridge is, however, taken with the cartridge in it.
2 - Next is the brass round, reported as Hungarian, and also .22 LR caliber. Note in the picture (hard to see at a glance) that the nose of the mock bullet is cut at a bias. OAL measurement of this cartridge is from the head to the highest part of the bullet nose. Since the chamber in this cartridge is off-center, so that the center-fire firing pin of the pistol will hit the edge of the rimfire cartridge used with the adaptor, I feel that the slanted tip is probably the method of insuring proper placement in the chamber of the insert cartridge. I think this is a poor design since I cannot see how this could be used in any way but single shot, with each adaptor cartridge placed by hand directly into the barrel. Trying to place them in a magazine at a correct attitude to fully enter the chamber of the barrel, with the chamber of the cartridge off-center, would be tedious in the extreme.
3 - The cartridge to the right is aluminum and reported to be Hungarian, and appears to be chambered for the 4 mm Übungsmunition. The chamber is bored on center, since the 4 mm cartridge is center-fire.
In the measurements, the measurements for the “bullet” refer to the reduced-diameter extension beyond the case length, regardless if shaped like a bullet or not. The case length for the DDR cartridge is to the flat from which the tubular-shaped bullet protrudes, at the top of the shoulder. So, the beveled shoulder is included in the case length measurement. The measurements of all cartridges, other than the case length of the DDR cartridge, fall into the specifications for the Makarov cartridge.
The East German adaptor cartridge is for the .22 Conversion kit, made in small numbers and very rare, for the Makarov pistol. We assume that if the other two adaptors are made in Hungary as reported, they would have been for some apparatus for the PA-63 pistol.
Below are the measurements for each each adaptor round. For each measurement there was actually a slight spread allowing for manufacturing tolerances. We have simply used what seemed to be the median measurement".
Adaptor Cartridge Measurements: