About VAMS column from the Dec. 28, 2015, Weekly issue of Coin World:
The Comprehensive Catalog and Encyclopedia of Morgan & Peace
Dollars by Leroy Van Allen and A. George Mallis describes a pair
of 1878 Morgan, Reverse of 1878 dollar die marriages that share a
remarkable obverse. Both are also included in The Top 100 Morgan
Dollar Varieties: The VAM Keys by Michael Fey and Jeff Oxman.
VAM-115 and VAM-198 are desired by most collectors because of the
tripling present on the obverse. Once spotted, the tripling is fairly
impressive. One of the most obvious areas is along the lower edges of
both cotton bolls. Also, a strong gouge is located in the top of the T
of LIBERTY, just to the right of its stand. This marker will survive a
considerable amount of circulation.
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While the obverse is relatively easy to recognize, its reverse mates
have historically provided some difficulty. VAM-115 is listed with a
“normal” Reverse of 1878 with a short nock or center arrow shaft. The
VAM-198, also of the Short Nock design, has an overpolished reverse
with a portion of the lower wing missing. The VAM-115 reverse can be
weak in this same area, and even moderate circulation can obscure a
fine detail like the degree of polished away design.
A far more reliable secondary diagnostic is the presence or absence
of an anomalous lump above the upper arrow feather. All of the Reverse
of 1878 dies were produced by the same hub, and this lump was present
on the hub. The relative strength of this feature varies among the
working dies. For the VAM-115 coin, this lump is nearly complete. By
contrast, the VAM-198 die has just a tiny nub showing on its earlier
stage, and none of this hub lump visible later.
There is not a great difference in value between the two varieties,
but most specialists actually want both marriages rather than two of
the same — one of which is misattributed.