Top of barrel marked 219 Zipper improved. The bottom of barrel under forearm is marked "28° 250 NK " and a "k" in a tringle. Anyone have any ideas what these stand for? TIA, moodyholler

I'll take a guess! Does it have a 28 degree shoulder and a 1/4" long neck?

I dug into C.S. Landis "22 Caliber Varmint Rifles".  Sounds to me as if you might have an Ackley-Improved Zipper.  That is the only one in the table of dimensions with a 28-degree shoulder. No neck length given, but case length is 1.92".  Lovell's Improved Zipper had a 30 degree shoulder, with 0.27" neck and 1.92" case length.  Kilbourn's K-Zipper has a 25-degree shoulder, 0.20" neck length and 1.89" case length.   

Landis wrote about the Ackley Improved Zipper, saying "the troubles which a reloader must watch for are legion and often serious and annoying".   

I would recommend a chamber cast.

waterman

Hello MH
An interesting sounding rifle. We seldom see .219" Zippers on my side of the pond, but in the USA just about every gunsmith of note in the first half of the last century tried to improve on the original.

There must be more variants or improvements of the .219 Zipper than almost any other rifle cartridge excepting perhaps the 30-06.

A chamber cast would be of great assistance to you. If the barrel is good (something not often found in needle blowers of that vintage) I'd keep it as such. If the barrel is shot out, then I'd say rebarrel to  a more useful round like the 45/90. Great for Long Range target work and a round capable of slapping down dead any game animal on the North American continent.

Harry