45 ACP * HP * .45 HP solved = ".45 Hirtenberger”

safe to presume “high pressure”; i.e., “proof” ?

I think they are too short!
434C Brandt-Muller.

overall 32.7mm
case 21.7mm
(with a cheap caliper)

I see it’s also called .45 Hirtenberg. For the Italians.

This is the shortened .45 ACP named .45 HP. As it is with the to 9x21 extended 9x19.
Legal issues of prohibited calibers.

Hirtenberger used knurled rims on HPT loads.

I do not doubt its Austrian heritage Does the second HP = “proof” ?

Thanks Dan & Alex

The caliber is named “.45 Hirtenberger” i.e. “.45 HP”.

The 12h position gives the factory which accidentally is also “HP”.

No “high pressure” here.

Think there is an old thread here which has a bunch of the boxes ot the ,45 HP illustrated

Reference: ECCC Bulletin No. 247, “The Cartridge Collector,” August-September 1985, Page 16, Item 247-23 by Austrian Ammunition Expert Josef Mötz, titled “Two new Austrian pistol rounds” is quoted below:

:“Owing to changes in Italian gun laws, this cartridge has been produced by Hirtenberger since May of this year (1985). It is identical to the .45 ACP except that the case is shorter by 1 mm. THE DESIGNATION IS ‘.45 HIRTENBERGER PISTOL’ (capitol letters by Moss, for emphasis of the correct name) and it is only produced for export to Italy, where the length of pistol cartridges is limited by law!”
So, the maker’s mark at 12 o’clock on the headstamp stands for “Hirtenberger Patronenfabrik” (HP) and the correct name of the cartridge-caliber marking of “.45 HP” is “Hirtenbeger Pistol.”

To my knowledge, this cartridge has only been made by Hirtenberger (Austria), GECO (Germany), Fiocchi (Italy) and Prvi Partizan (Serbia). I have specimens from each in my own collection, although regrettably, a search indicates I have not one single box for this caliber in my collection, so sorry, no box pictures.

John Moss

I guess I should learn to try multiple search @ 45 HP; .45 HP; ,45 HP; etc…

Pete - it seems I should have two .45 HP boxes in my collection, Geco and PPU. I will have to try another search. I found nothing earlier. Thanks for the web link.

Rather than a new answer, I will edit this one to give you a great big hug and thank you, Pete, for posting that link. I found that I had four .45 HP boxes in my collection, three from PPU, Serbia (and so marked - made in Serbia) and one from Geco, Germany.

I do not have any from Hirtenberger nor from Fiocchi, which is a real gap, since the first rounds were made in Austria for Italy! All of my boxes basic labels are shown on the old Forum thread that Pete so kindly supplied. No need to picture them here, again.

John Moss


Are the rounds desirable to collectors or common ? (In the U.S or more specifically at SLICS ‘21 ?)

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Pepper - if you don’t have one and want one, any cartridge is desireable to collectors, whether common or not. I have nine or ten variants in the .45 HP round, but have not added one in several years. I don’t think some of the variants are very common now, especially in the US, although others, like the PPU, are common. I had full boxes of both of their loadings. I don’t even recall what I did with all the surplus, since I don’t like full boxes generally - damage waiting to happen.

John Moss