I do some volunteer work at a local archaeology dig. Here is some of what came into the lab today. It has been too hot to do any digging lately so I thought some of you might like to see this.
It is a bit out of date but Dean Thomas' book "Ready, Aim, Fire" indicates that "swaged" bullets have been found at all Corps areas except for the 6th and 12th. Honestly by July 1863 there were so many "pressed and turned" swaged bullets being issued to the Army of the Potomac that the 6th and 12th probably had them too.
'For about five years I extensively dug a brigade winter camp of the 5th Corps used up to the beginning of the Gettysburg campaign May/early June 1863 and I found them there but they were vastly outnumbered by standard .58's and Williams Regulatuon Minies.
I don't know about Gettysburg, but in all my years of relic hunting around Vicksburg, I never dug a swaged bullet. I only have one in my collection, and I dug that particular bullet at Port Hudson, Louisiana.