There is a mis-named index to 'Civil War Pension Files', microfilm of cards created in the 1930s. The National Archives Micropublication number is T-288. There are 544 (count 'em) microfilm rolls arranged alphabetically by soldier.

A really horrible image of a card for one George E. Russell is on Ancestry.com, with service 1875-1880 in what might be D Company, 2d US Artillery. The pension claim number is 2296938, with a prefix that could be 'A' or could be 'R'--very hard to make out. He served from California (as did some of my own Maine relatives).

A widow's application for pension is not listed on the card. The time period for the index ends in 1934, it is possible that a widow applied after that date.

You can write the national archives for a copy of his service record and a copy of the claim file by submitting form NATF Form 85 to the National Archives and Records Administration, Attn: NWCTB, 700 Pennsylvania Avenue, NW, Washington, D.C. 20408-0001.

You can request NATF Form 85 by submitting your name and postal address, the form number (NATF Form 85), and the number of forms you require (limit 6 per request) to inquire@nara.gov. Or you can go to their web site where there is a way to order the files using a credit card. Requests for the service record and for the pension file are two separate transactions, requiring 2 requests and forms. Be sure to specify that in each case you want the whole file. I am not familiar personally with pension files for service in this period, but for Civil War service there are often all manner of interesting affidavits from relatives and neighbors and sometimes from fellow soldiers.

There were other George E. Russells in the 'Pension' index, but all seem to be regarding Civil War service.

Good hunting,
Jade