Sorry I don’t have the time to edit this, from my “Mahrholdt” E-file. I do have the first seven or eight of his books, a must for anyone interest in the German-Austrian gunmakers.

Richard Mahrholdt lived from 1878 to 1949. From 1898 to 1918 he was head of Tiroler Waffenfabrik Peterlongo Richard Mahrholdt & Sohn (Tirol gun factory P. R. M. & son) in Innsbruck/Austria. That factory was founded by Johann Peterlongo in Innsbruck in 1854.
In 1919 he founded R. M. & Sohn, which overtook the Tiroler Waffenfabrik again in 1939. After Richard Mahrholdt's death his son became head of the firm.
The production of Tiroler Waffenfabrik Peterlongo R. M. & Sohn (according to "Waffenlexikon" of 1957):
• target rifles
• rifles for high power cartridges and repeating rifles
• drillings
• side-by-side rifles
• over-and-under rifles with different calibers
• over-and-under shotguns
• over-and-under rifle-shotguns
• scope mounting
R. Mahrholdt was in good contact with the Suhl gunsmith August Schüler. In his time he was known as a good expert of gunnery. He is the author of the "Waffenlexikon", which was published in 1931 and its second edition in 1937. This book is even today in publication and revision.

More on Richard Mahrholdt
Mahrholdt was one of the biggest gun gurus of prewar Germany. He was also a master gunmaker with a safety Drilling of his own design. His greatest legacy was the "Waffen-Lexicon", first published in 1931 followed by editions in 1937. It is still in print, but has been heavily edited so that the good info on older makers has been lost. If you can find the 2nd edition, get it. It is a treasure trove of gun lore, patents and company profiles now lost to posterity.
Mahrholdt managed the Peterlongo guns works in Innsbrück, Austria from 1898-1918 after which he took over as his own under the name of Tiroler Waffenfabrik Peterlongo, Richard Mahrholdt und Sohn. After Mahrholdt's death in 1947, it was taken over by his son, Herbert, who was also co-author of later editions of Waffen-Lexikon. The Tiroler Waffenfabrik (Tyrolean Arms Factory) closed shop some time in the 1970s.