Yes, General, apparently there were a couple of problems associated with the breech loading mechanism on the Whitworth, in general (no pun intended). Copper seals were provided to prevent gas leakage in the breech during firing. These seals were short-lived and therefore allowed powder residue to build up causing the mechanism to jam. Frequently, for whichever reason, breech-loading was suspended and the rifle was loaded from the muzzle. Perhaps it is this residue induced jamming that you are referring to although this is purely speculation. I would suspect numbers 3 and 4, who serviced the breech during firing, were the recipients of some unwanted residue as well!
The accuracy of the Whitworth was unparalleled during the war. "During a test trial in Southport Sands, England, in 1863, a 12-pounder breech-loading Whitworth rifle hit a target from 4.7 miles away."
http://aotw.org/weapons.php?weapon_id=19
According to the below referenced National Park Service marker at Gettysburg the Whitworth did see active service during the battle.
http://www.virtualgettysburg.com/exhibi ... ct149.html Here is a reference to part of that action of the Whitworths at Gettysburg:
http://books.google.com/books?id=wcP3h8 ... t&resnum=2
At least one Whitworth served with Hunts Battery and one more with Sumter (GA) Artillery, Battery E "Irwin Artillery, Lane's Battery" during the Sharpsburg campaign although I do not know if these are the same two guns re-ordered during a reorganization of the ANV artillery. Both of these units were part of Jackson's Corps at that time.
There are several photos of the Whitworth available on the net including:
http://www.flickr.com/photos/duddyd2003/3564428382/ The original English drawings show a distinctive carriage that not only included an elevating screw but a traversing mechanism as well that allowed the gunner to move the barrel horizontally. Apparently this carriage was not utilized by American forces; rather an American style carriage was adapted. According to one CW artillery historian, the trail was lenthened to accomodate the length of the gun tube and location of the elevating screw.
Hope this is of general interest and provides some additional "food for thought."
Jack Hanger
Fremont, NE