Here is that Big 5 1931 Izhevsk M91/59. (The receiver is also a 1931 Izhevsk.) That the stock is Beech and the way it is made have me wondering if it was made specifically for the M91/59. First, it is not likely WW II vintage. It appears "newly" made, but is cut for the earlier receiver with a narrow tang. It has no stock mortise for the M38 or M44 style carbine rear sight mounting sleeve. Since it also lacks a bayonet relief cut, I do not think that it was made for either of those two carbines. Often a M91/30 stock when cut down for use on a M91/59 will have a horizontal notch on the front tip of the stock under the nosecap. It is a remnant from the original SSE cut. This stock doesn't have that notch. (This is not conclusive as I doubt that the SSE cuts were located with consistent precision.) So, it may not be a cut-down M91/30 stock. The stock uses the folded-tab sling slot insert in front and the push-in type insert in the rear. The buttstock does have a small toe splice and its left side has three atypical rectangular patches. The top of the buttstock has the boxed "17" and the double-boxed "20" - Bulgarian marks? Has there been a recent import of Soviet weapons from Bulgarian stores? The Century import mark is of a different style than I have seen before. Also, the stamped numbers on the floorplate use the "standard" Soviet "three" (style matches the barrel), but the buttplate and the bolt use the Cyrillic "3" (Z) as threes! Odd...as if made for the American market as we use both styles of threes. Why put Z's in the body of a serial number? DDR