For those interested in flare cartridges’ (I do not know anything about Polish flares) here is a recent post from the reibert.info Forum. Posted by “Yuber”:
Note that the 3 flare cartridges shown in the photos appear to have been recovered from the ground after many years.
Below is a Google translation of the post and photos posted by Yuber:
"Here is another set of Poles that Comrade Petya Sitnik has kindly shared with me: The set consists of 3 rounds with different lengths of brass sleeve. 4th caliber (26.5mm). Sleeve length: - short - 100mm; - medium - 115mm; - long - 180mm. It is curious that the short sleeve is the base for all 3 sleeves. The middle and long sleeves are obtained by increasing the length with the help of an additional shell of a smaller diameter (25 mm), inserted inside the short sleeve. It turns out such a stepped design. The junction is clearly visible in the photo."
"From falling out of the sleeve, the upper shell is fixed by spot soldering of rather rough work. Interestingly, the bottom of the sleeve is not completely stamped at the same time with the sleeve, as on German PMV brass sleeves, but is a separate part of shallow stamping (as on folder sleeves) pressed into the lower shell. Obviously, the Poles before the war did not have production facilities for deep stamping of such cartridges, and therefore were forced to refine their work on inventing solutions to this problem.
The marking on the bottom is shallow: the letter W (obviously Warsaw) and the year 41. There is also a fuzzy mark, similar to the coat of arms of Poland.
Application. In short sleeves, signal cartridges were equipped, in long - illuminating parachute. The purpose of the middle sleeves is not entirely clear. Perhaps they were used to equip smoke cartridges.
Sleeves are interesting precisely for their ingenious, although not entirely perfect design."
The second photo tries to show the headstamps, from what I can see there is " W.A.1. " at the 6:00 position, not " W 41 " as stated by Yuber.
Can anyone provide additional information about these modified flares?