In the Army of Northern Virginia, batteries were often split up because they were composed of multiple types of cannon and so guns were doled out based on situational need. Here are the batteries' composition at Gettysburg (based on Busey and Martin's Regimental Strengths and Losses at Gettysburg since there are some questions about some of the batteries):
FIRST CORPS
Henry's Battalion
Branch's Battery: 3 Napoleons, 1 12-lb Howitzer, 1 6-lb field gun
Charleston Artillery: 4 Napoleons
Palmetto Artillery: 2 Napoleons, 2 10-lb Parrotts
Rowan Artillery: 2 Napoleons, 2 3" Rifles, 2 10-lb Parrotts
Cabell's Battalion
Manly's Battery: 2 Napoleons, 2 3" Rifles
Troup Artillery: 2 Napoleons, 2 10-lb Parrotts
Pulaski Artillery: 2 3" Rifles, 2 10-lb Parrotts
1st Richmond Howitzers: 2 Napoleons, 2 3" Rifles
Dearing's Battalion
Fauquier Artillery: 4 Napoleons, 2 20-lb Parrotts
Hampden Artillery: 2 Napoleons, 1 3" Rifles, 1 10-lb Parrott
Fayette Artillery: 2 Napoleons, 2 10-lb Parrotts
Lynchburg Artillery: 4 Napoleons
Washington Artillery
1st Company: 1 Napoleon
2nd Company: 2 Napoleons, 1 12-lb Howitzer
3rd Company: 3 Napoleons
4th Company: 2 Napoleons, 1 12-lb Howitzers
Alexander's Battalion
Madison Artillery: 4 24-lb Howitzers
Brooks Artillery: 4 12-lb Howitzers
Ashland Artillery: 2 Napoleons, 2 20-lb Parrotts
Bedford Artillery: 4 3" Rifles
Parker's Battery: 3 3" Rifles, 1 10-lb Parrott
Bath Artillery: 4 Napoleons
SECOND CORPS
Latimer's Battalion
1st Maryland Battery: 4 Napoleons
Alleghany Artillery: 2 Napoleons, 2 3" Rifles
Chesapeake Artillery: 4 10-lb Parrotts
Lee Artillery: 2 20-lb Parrotts, 1 10-lb Parrott, 1 3" Rifle
Jones' Battalion
Charlottesville Artillery: 4 Napoleons
Courtney Artillery: 4 3" Rifles
Louisiana Guard Artillery: 2 3" Rifles, 2 10-lb Parrotts
Staunton Artillery: 4 Napoleons
Carter's Battalion
Jeff Davis Artillery: 4 3" Rifles
King William Artillery: 2 Napoleons, 2 10-lb Parrotts
Louisa Morris Artillery: 4 Napoleons
Orange Artillery: 2 3" Rifles, 2 10-lb Parrotts
Dance's Battalion
2nd Richmond Howitzers: 4 10-lb Parrotts
3rd Richmond Howitzers: 4 3" Rifles
1st Rockbridge Artillery: 4 20-lb Parrotts
Powhatan Artillery: 4 3" Rifles
Salem Artillery: 2 Napoleons, 2 3" Rifles
Nelson's Battalion
Amherst Artillery: 3 Napoleons, 1 3" Rifle
Fluvanna Artillery: 3 Napoleons, 1 3" Rifle
Milledge's Battery: 2 3" Rifles, 1 10-lb Parrott
THIRD CORPS
Garnett's Battalion
Donaldsonville Artillery: 2 3" Rifles, 1 10-lb Parrott
Norfolk Artillery: 2 Napoleons, 1 3" Rifle, 1 10-lb Parrott
Pittsylvania Artillery: 2 Napoleons, 2 3" Rifles
Norfolk Light Artillery: 2 12-lb Howitzers, 2 3" Rifles
Poague's Battalion
Albemarle Artillery: 1 12-lb Howitzer, 2 3" Rifles, 1 10-lb Parrott
Charlotte Artillery: 2 12-lb Howitzers, 2 Napoleons
Madison Artillery: 1 12-lb Howitzer, 3 Napoleons
Warrenton Artillery: 2 12-lb Howitzers, 2 Napoleons
Sumter Artillery
Company A: 1 12-lb Howitzer, 1 Napoleon, 1 3" Rifle, 3 10-lb Parrotts
Company B: 4 12-lb Howitzers, 2 Napoleons
Company C: 3 3" Rifles, 2 10-lb Parrotts
McIntosh's Battalion
Hardaway Artillery: 2 3" Rifles, 2 Whitworths
Danville Artillery: 4 Napoleons
2nd Rockbridge Artillery: 2 Napoleons, 2 3" Rifles
Johnson's Battery: 4 3" Rifles
Pegram's Battalion
Pee Dee Artillery: 4 3" Rifles
Crenshaw's Battery: 2 12-lb Howitzers, 2 Napoleons
Fredericksburg Artillery: 2 Napoleons, 2 3" Rifles
Letcher Artillery: 2 Napoleons, 2 10-lb Parrotts
Purcell Artillery: 4 Napoleons
CAVALRY
Beckham's Battalion
1st Stuart Horse Artillery: 4 3" Rifles
2nd Stuart Horse Artillery: 2 Napoleons, 2 3" Rifles
Ashby Horse Artillery: ?
2nd Baltimore Light Artillery: 4 10-lb Parrotts
Washington Artillery: 3 Blakeley Rifles
Lynchburg Horse Artillery: ?
Other than being a logistical nightmare, finding the right guns for the right situation would have required distributing guns on an as needed basis.
Ryan