Do you know what models your TOZ's are? I have a Tula 16 gauge. I corresponded with a fellow from Russia and he believes mine was made in the period 1922 to 1932 but he was leaning more to the early 20's. He said it is a TOZ-B and wears barrels from before WWl. It too has a POW grip and 2 1/2" chambers. It has a short length of pull though but I was told it likely came out of the factory that way. It is a nice little field gun.
That's always been in question. I've never seen a specific model number on a document with this model pictured. TOZ-66 is the model number most often associated with the model. My 12 gauge indeed has "TO3-66" engraved at the breach end of the barrels, next to the rib on both sides. The rest of the space is filled with a simple "IoIoIoIoI" pattern.
My 16 gauge has "6M-16" engraved on both barrels in that same position. And, has the same "IoIoIoIoI" pattern the rest of the way.
My 20 gauge has a different pattern that looks like pineapples in that space, and no numbers or letters of any kind. It does have the TOZ triangle logo on both barrels, above the pineapples, which neither of the other gauges have.
If you weren't aware, these guns are stocked in Birch. I've refinished all 3 of mine and they can be quite nice with a dark walnut stain and a hand-rubbed finish.
ETA: The stocks on mine are all in the 14 1/2 to 14 3/4 range, so yours was probably shortened. And, yes, I agree wholeheartedly, these are excellent field guns in every way. They're practically indestructible, yet they're well balanced, well regulated, reliable and scandalously inexpensive. Parts might be an issue. I've owned all 3 of them for 10 years or more, torn them apart to refinish them, and have never needed a replacement part. Barring abuse, I doubt I'll ever need parts for them. But, for me, the open hammer style and little touches borrowed from the Brits (such as the rounded edges on the receiver that make one-handed carry at the balance point possible) are the bonus. For non-steel purposes, this model is a well kept secret.