7.7mm (.303) API Cutaway

Need help with a 7.7mm blue tip Spotter/ Explosive? Was told it was written up once in a 1974 IAA journal and was hoping that some one can enlighten us with there vast knowledge on the subject. Never seeing the journal article, would this be more of a spotter or an explosive round. Also is this part of the series of API that have the 4 indents at the tip made by the same?
Very hard steel core with a loose lead sleeve for the cannalure/ crimp, white phosphorous filled tip. There is a dent or impression in the blue tip that does not go all the way thru, but is filled with solder. You can see this best on the section on the right.
Thanks for any help. Kevin
(Edited title for reference, Thanks Brian!)

See this EXCELLENT article (by Giovanni Defrancisci ) : munizioni.eu/ )

Quote from the above article:

"Tipo perforante speciale 4° tipo / AP special type (SMI 1942 / 43)

Armor-piercing Incendiary phosphorus /phosphorus API type

10,00 / 10,10 g.
Acciaio placcato tombacco con punta in rame, nucleo in acciaio con fosforo in punta
Nickeled steel ball with copper tip, steel core with phosphorus tip"

Below is from The INTERNATIONAL CARTRIDGE COLLECTOR, Vol. 3, #2, Dec. 1974/Jan. 1975. An article by Alessio Grimaldi on Italian Ammunition, pp. 20 -30 (drawings by E.L. Scranton)

Pages 26 -27:



Nice sectioning, as always!