Piovi - I think those are the only makers. I have the following in my collection, and have not seen others, although surely dummies exist, if for no other reasons than from Trade Shows.
- HP * 45 HP Ball, FMJ RN; Proof, FMJ RN coarsely knurled rim; Proof, FMJ RN, finely knurled rim). All are plain brass case.
Geco .45 HP Ball, plain brass case, FMJ RN; Ball, nickeled case, FMJ RN; Ball, plain brass case, lead SWC. All three of these have the primer completely lacquered red.
G.F.L. 45 HP Ball, plain brass case, FMJ RN; Ball, plain brass case, FMJ SWC.
The Fiocchi rounds have flat nickeled primer cups with those from Hirtenberger are domed brass cups.
I don’t know of any other makers of this cartridge. It has never been offered in the United States, that I know of.