US made 20x102 HEI with black bars

I just came across this image in a Chilean anniversary publication of FAMAE.

I do not recall having seen such projectiles with black bars above and on the sides of the usual markings.
One similar I saw from NWM (Holland) but there the top bar is missing.

Could somebody explain what these bars are indicating?

The Dutch one (source: internet).

I may be very far off, but those look like some kind of packaging marks / rubs or perhaps the border(s) of the marking stamp / stencil.

No idea what the lines indicate, but i’ve got a similar marked TP round (with white lines…)

projectiel1 projectiel2 projectiel3

Interesting, I never saw this on TP loads.

Now I see that you mean, I was way off & new to me.

Orpheus, who is the manufacturer of your TP projectile?

Looks to me part of the pad ‘block’ used to ink/paint mark the projectile, so it has a square form to line up the shell?.

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As far as i know, SIO made this projectile, but that Mfr. code is unknown to me.
The projectile was on a ‘WM’ marked M103 case, but not sure case and projectile belong together.

Found this one in my drawers.
Electric primed, blue colored insulator, no headstamp & inerted, case stamped in black ink “20MM, M103 RND-2-368 (not sure about these 3 numbers)-70”.
A bit faint but again an M55 A2 “KO-10-3” & I think Harvey Aluminum? HA -7-5-71


In my opinion the bars were not used to identify something in particular, but just to clearly distinguish the identification markings of the manufacturer of the projectile from the markings of the manufacturer that loaded/assembled the cartridge.

In the US, it was applied by at least two different Olin loading and assembly operations: Indiana (KO) and Marion (WG). The latter identification symbol is not listed as assigned to Olin in any military handbook that I know of, but it is found in cartridges loaded at the Winchester Group Olin’s Technical Systems Operations located in Marion, Ilinois.

From a brochure dated c. 1977-80:

Fede, and the Dutch copied this practice and then all stopped ?

Don’t know about the Dutch connection, but Olin did this for more than 10 years.

Were any other medium caliber cartridges observed with such markings?