I read a short story in the mid-90s
"Frost and Thunder", a novelette by Randall Garrett; first published in Asimov's SF Adventure Magazine, Summer 1979, which is available at the Internet Archive. You may have read it in the 1986 paperback anthology Time Wars edited by Poul Anderson, Charles G. Waugh, and Martin H. Greenberg, or else in the 1992 hardcover anthology High Adventure: Tales of Exploration, Escape, and Intrigue edited by Cynthia Mason and Charles Ardai. Does any of these covers ring a bell?
which was fairly similar to Poul Anderson's "The Man Who Came Early." Different from that story, this was told from the modern protagonist's point of view. Theodore, the main character, was an avid combat pistol shooter who traveled to Sweden (or another Scandinavian country) to visit a friend,
Anyway, I got this letter addressed to me, Theodore Sorenson, with a Stockholm postmark. Sten, so he claimed, had introduced combat pistol shooting in Sweden, and had built a range on his property. He was holding a match in September, and would I come? There would be plenty of akvavit.
ventured out into the misty woods, and traveled back in time.
No mention of mist. Theodore goes out to practice his shooting:
It was cold outside, but there wasn't much wind. I saw the dead pine, and headed for it.
Night comes on slowly in the north, but it comes early east of the Kjölen. Those mountains make for a high horizon.
Sten had, indeed, used that pine for target practice; he'd painted a six-inch white circle on it. I went up to the pine, then turned to pace off twenty-five yards.
I was at twenty paces when the wind hit.
I don't know how to describe what happened. It was like a wind, and yet it wasn't. It was as if everything whirled around, and then the wind came.
And I was in the middle of the goddamdest blizzard I had seen since the time I nearly froze to death in Nebraska.
There he encountered a pre-Viking people
They were heavily clad in dark furs, like Eskimos wearing black bearskins. Each one carried a long spear and a roundshield.
They weren't Eskimos. Eskimos don't have blue eyes and blond hair. Those blue eyes regarded me with suspicion.
who were dealing with a Beowulf-style menace.
His shaggy gray eyebrows lifted. "You know not? Truly, you are from afar. They are the demons, the Evil Ones, the Eaters-of-Men. They are from the Far North, and they come to slay and to eat. They speak as do animals. They are Giants!" He paused. "Not so great as you, but Giants, nonetheless." Another pause. "And they wear frost about them instead of furs, as decent folk do."
Notably, they had problems pronouncing his name... Tador, or something like that.
"You speak well, Giant Tay'or," Vigalaf said. He raised a hand. "Bring him food."
He helped his allies beat the bad guys, but only with the help of his pistol,
They came at us, spears at the ready. When there was twenty yards between the two opposing ranks, I tossed away my spear and shield, dropped to one knee, and drew my pistol.
The thunder of that weapon echoed across the snowfield as I placed each shot. I think my own men hesitated when they heard that noise, but they charged on when they saw it was me doing the damage.
They didn't know what to make of it, but they saw the Demons, the Eaters-of-Men, fall one after another, and they knew I was doing my part, as I had promised.
Forty-five caliber hardball slugs from service ammo does more damage to living flesh than any other handgun ammo in existence. A man hit solidly with one of those bullets goes down and stays down.
I fired as if I were firing at pop-up targets, except that there was no "friend-or-foe." If it was wearing a polar-bear suit, it was a foe
which the locals thought was a hammer thrown with a clap of thunder.
I think I know what happened. I remember hearing Hrotokar in the background saying: "His hammer smashed them! Killed them! And then came back to his hand!"
I can see how that illusion could come about. I hold the hammer in my hand and there is a thunderbolt and the foe falls dead—his head smashed in. And then the hammer is back in my hand. Sure.
Those folk had already shortened my name from "Teydor" to "Tey'or"; why not one syllable further?
Then the mist overtook him and he returned to his own time,
There was no snow on the ground. I was alone in the forest.
Before me was the dead pine that Sten Örnfeld had drawn a target on.
I turned. There was Sten's lodge, fifty yards away.
I went toward it. It didn't fade or go away. It was solid, as it should be. Somehow, some way, I was back in my own time.
naming his pistol Mjolnir with a quote, "ja, the original."
My weapon has a name now, as Sten suggested. I looked up a man who knows Norse runes, and I had another man engrave those runes on my pistol, on the right, just above the trigger.
The engraving says: Mjolnir.