The following narrative, with minor editing, is from my "Silver Dollars & Trade Dollars of the United States: A Complete Encyclopedia" (Wolfeboro, NH: Bowers and Merena Galleries, Inc., 1993)
Numismatic Information
Hoard coins: Throughout the 1950s, a small but steady stream of Uncirculated 1881-O dollars trickled into the market. Occasionally, a bag would surface and be broken up and absorbed into dealer stocks. Philip Maul advertised rolls of this date in The Numismatist in September 1953. In the same publication in September 1957, Harry J. Forman advised readers that he had 1881-O dollars in quantity. Beginning in October 1962, many additional bags of 1881-O dollars were released by the Treasury Department, a dispersal which continued through at least the summer of 1963. Up to that point, 1881-O dollars were somewhat scarce, although hardly rare, in Mint State preservation.
Circulated grades: High-grade circulated coins are very common (see "Two-Beer" Dollars under Additional Information below), as are well-worn pieces. The "two-beer" dollars came from Federal Reserve branch banks at Helena and Missoula, Montana; others from the Continental-Illinois Bank hoard.
Mint State grades: The 1881-O is very common in lower Mint State grades from MS-60 through 62. At the MS-63 level I estimate that 50,000 to 100,000 exist. In MS-64 it is slightly scarcer but still quite available. In MS-65 grade, well struck, the 1881-O is hard to find. Probably, only 1,000 to 2,000 MS-65 or finer pieces survive. The yellow flag of caution goes up for anyone wanting to buy an MS-65, even a certified or slabbed coin, for an MS-65 is apt to cost many multiples of the price of an MS-64, and the actual technical grade difference is slight. Be careful!
The striking of 1881-O dollars is average. Indi-vidual specimens range from flat to well struck. Cherrypicking will pay dividends with this date.
Prooflike coins: Prooflike coins are common, but most are in AU or very low Mint State grades. Probably about 4,000 to 8,000 exist MS-60 PL or finer, all but a few being lower than MS-65. Many prooflikes are one-sided. In the DMPL column, the 1881-O is about equally available, but hardly any are better than MS-64 DMPL. The "Proof' in "World's Greatest Collection" (F.C.C. Boyd), at a then very high $50, has not been traced. Nor has the Jack Roe coin at $115 (1945?), reappearing in Bolender's 183rd Sale (2/23/52), at $67.50. All these prices exceeded Philadelphia's Proofs of the period. On the other hand, the one B.M. Douglas advertised in The Numismatist 12/51 at $17.50 was probably a DMPL.
Varieties
Circulation strikes:
1. Normal issue. Medium-size 0 mintmark:Breen-5559. 26 VAM varieties.
2. "1881-O/S" (status controversial): A variety described as 1881-O/S, Breen-5560, has been cited by Walter Breen (B-5560), but has not been confirmed by others. Leroy C. Van Allen and Bill Fivaz each report that they have never seen such a variety; Van Allen suggests that VAM-5 or 9 might be mistaken for an overmintmark. Thomas K. DeLorey believes it is just a repunched O. Jeff Oxman believes that it may indeed by an overmintmark, "but the jury is still out; it has similarities with 1882-O/S varieties.(Bill Fivaz and Leroy C. Van Allen letters to the author, each dated October 31, 1992. Thomas K. DeLorey note received November 1992. Jeff Oxman, letter to the author, November 29, 1992.)
Dies prepared: Obverse: 55; Reverse: 40
Circulation strike mintage: 5,708,000
Estimated quantity melted: Unknown, but probably many under the 1918 Pittman Act.
Availability of prooflike coins: AU prooflike coins are common, but there is little demand. Mint State PL and DMPL pieces are readily available but are mostly in lower grade levels.