Agersta Chisels
My friend, Randall Nelson, brought these chisels to my attention. He’s the only person I know who has a chisel with the “Agersta” mark stamped on the blade.
The Agersta chisel is the one at the bottom of the photo below. It bears other blade imprints on the front of the blade, including “MADE IN SWEDEN”. It shares this imprint with the other two chisels in the photo. It’s possible that they all came from the same factory. The blades also seem rough on all of these chisels, appearing to have never received a final finish. All of them have birch handles.
The backs of all of the chisels are also rougher than usual. The chisel with the Agerta stamp is the one on the far right.
The imprints on the blade read: “AGERSTA / 1.00 / MADE IN SWEDEN.” 
Here is a close-up of the mark stamped that is combined with“MADE IN SWEDEN”. It appears to be an “å” or an “ä”. “Agersta” is typically spelled “Ågersta” in Swedish.
Hmm. It appears that the first A in Agersta is lower than the last A in the word. So Ågersta could be the most probable word. But although there is a village called Ågersta it returns very few hits and I haven’t fold any information about tool makers in that area. To me the stamp looks little bit homemade, more like a owner’s mark or a stamp used for marking tools owned by for example a school, woodworking shop or other facility.
I had similar luck trying to track down the Ågersta location in Sweden. The markings on this chisel are still very much a mystery to me.
The stamp should probably have said: “Fagersta”
From Wikipedia:
Geography[edit]
The city is located at the junction of two railways between Ludvika-Västerås and Avesta (Krylbo)-Örebro, in the heart of the historic Bergslagen region which is rich in copper and iron ore. There has been mining activity in the Fagersta area since the 15th century but it was not organized until the 17th century and was not made a corporation until 1873, when Fagersta Bruks AB was founded.
History[edit]
Fagersta was made a city in 1944 when the industrial hot spot of Fagersta merged with its service-oriented neighbour Västanfors. It is now the seat of Fagersta Municipality.
Industry[edit]
Today’s industry is focused on hard metal tools (Seco Tools AB and Atlas Copco Secoroc AB) and stainless steel products (Fagersta Stainless AB and OUTOKUMPU Stainless Tubular Products AB).
I notice that the stamps are on an area that is usually tempered. ?
Yes. Parts of the blade stamps appear to be in areas that may have been hardened and tempered.
Perhaps they were stamped after the blade was softened (annealed) and shaped, but before hardening and tempering.
I was curious about the hardening and tempering of a Gensco chisel a short while ago. I dipped the blade into a mild solution of citric acid and water to reveal the quenching line and found that it was hardened only half way up the blade. You can see my post on this here:
https://galootopia.com/old_tools/gensco-blade-hardening-new/
Berg used to brag in their ads that they were hardened 3/4 ways up the blade, so it seems that not all chisel manufacturers went that high.
I have a set of 6 of these chisels. They are stamped “Made in Sweden” No maker’s mark. Although they are a bit labor intensive to set up, the steel is excellent!