I have a very accurate little 32 cal in-line. It looks like a standard single shot bolt action 22 rimfire, but in front of the bolt is a nipple for a No 11 perc cap, instead of a chamber. When the bolt is closed the ignition area is enclosed. The barrel is marked Marathon Arms, Connecticut. It also says "Made in Spain."
I bought it in 1986 or 1987, at a gun show in Richmond VA, brand spanking new for $35.00. The reciever is even grooved for a 22 scope. I have placed 5 shots in a one inch square off hand at 25 yds with the open sights it came with.
I have tried to find the company again with no luck. It is a very handy little gun. The only draw back is the lack of place for the ram rod. In my closet full of winter projects, I have an old single shot 22 rimfire bolt gun, that I thought I would try to convert to a muzzle loader. I even have a 38 caliber smooth bore barrel I was going to use on it. Figured I could shoot ball or shot.