You may already know this, but the S. P. Bates "History of the PA Volunteers" states that the 116th was equipped with "the smooth-bore Springfield musket for buck and ball."

As far as photos, here are some on-line sites that contain Civil War pictures:

The Library of Congress,
http://memory.loc.gov/ammem/cwphtml/cwphome.html

Daguerreotypes at the Library of Congress
http://rs6.loc.gov/ammem/daghtml/daghome.html

The National Archives:
http://www.archives.gov/research_room/research_topics/civil_war/civil_war_photos.htm

The U. S. Military History Institute
http://carlisle-www.army.mil/usamhi/

This site discusses the four main photographers of the CW era:
http://www.ipeters.de/photography.html

CW photos by Gardner, who worked for M. Brady before going on his own:
http://www.southernphotos.com/history.html

The Civil War Center at Louisiana State University has a
page of links to sites with photos:
http://www.cwc.lsu.edu/cwc/links/photo.htm

Steve Recker's Virtual Gettysburg:

http://www.virtualgettysburg.com/exhibit/monuments/

http://www.civilwarphotos.net/

This commercial site has over 1200 civil war photos: http://www.picturehistory.com/find/c/289/p/15/mcms.html
Kevin's Civil War Photographs
http://www.geocities.com/kevman9802/
Kevin's Peninsula Campaign Photos:
http://www.geocities.com/kevman9802/Pennisular.html

Virginia Civil War Archive: Images from Harper's Weekly Magazine
http://www.aladin.wrlc.org/gsdl/cgi-bin/library?t=0&p=about&c=vacw

The American Civil War: Photos
http://www.swcivilwar.com/cw_photos.html

American Surgical Antiques, pre-1870: 1500 photographs (and articles) of Civil
War surgical instruments, kits, amputation and surgical sets.
http://www.braceface.com/medical/

Civil War Homepage
http://www.civil-war.net/
Civil War Homepage Links to Photos:
http://www.civil-war.net/searchlinks.asp?searchlinks=Photos

Modern Photos of Civil War Sites
http://www.civilwaralbum.com/
Modern Photos of Civil War Sites: Peninsula Campaign
http://www.civilwaralbum.com/misc/peninsular1.htm

Selected Civil War Photographs, Library of Congress
http://memory.loc.gov/ammem/cwphtml/cwphome.html
Daguerreotypes at the Library of Congress
http://rs6.loc.gov/ammem/daghtml/daghome.html

Photographs from the Civil War, Part I
http://www.wildwestweb.net/cwphotos.html
Photographs from the Civil War, Part II
http://www.wildwestweb.net/cwphotos2.html

Malcolm's Modern Photos of Civil War Battlefields
http://www.angelfire.com/va2/ageofmalcolm/photoindex.htm

You might also try the historical society or library of the county(ies) where the regiment was recruited. These local sources are probably the best source for finding regimental histories, dairies, photos of individuals, etc.