This nice example of a 20-pounder Parrott rifle is in terrific shape: its limber, carriage, barrels and all other things weaponry are in terrific condition. These rifles are more rare than the 10-pounder Parrott rifle as well as the 3-inch ordnance rifles and the Napoleons which seems to be everywhere. The Parrot is very similar to the 3-inch ordnance save for the band around the breech which makes it distinguish itself from the 3-inch ordnance. Also, some Parrott have a flare at the end of the muzzle (eliminated in 1863) and the 3-inch does not. Another similarity the two rifles share is the deep incised stamp that runs along the outer muzzle which make identification very easy and accurate. Curiously however, this Parrott rifle does not have any identifying marks on it. As a result, this guns is anonymous as I could not recover the registry or foundry numbers.
The manufacturing of the gun carriages is an interesting story. After the war, Calvin Gilbert conducted a foundry @ Gettysburg and manufactured metal gun carriages to replce the rotted wooden ones. He also cast the battery tablet at this site as well as the other ones about the battlefield. Gilbert joined the 87th Pennsylvania Volunteers when the "Rebellion" broke out. Since he was musically inclined, he was made a member of the regimental band. In early 1863, he was promoted to the rank of Captain and sent to Washington D.C. for commissary duty. He served in that capacity until the war ended in 1865, and at war’s end earned the brevet rank of Major. 
After returning home to Gettysburg, Major Gilbert moved his family to the town of Chambersburg, where he served as the Superintendent of Schools. He also opened an iron foundry there in 1868. When Calvin learned, nearly thirty years later, in 1894, that the Gettysburg Foundry was available, he purchased it with a business partner & moved his family back to Gettysburg. For the next twenty years, the Calvin Gilbert Foundry created ironworks that are still seen today on many historic forts and national battlefields (this tablet), from upstate New York to Florida to Lookout Mountain. Gilbert lived to be 100 years old and attended the Last Reunion of the Blue and Gray for the 75th anniversary of the Battle of Gettysburg when he was 99. He was a most remarkable man who lived an amazing life.
There is an excellent excerpt in the American Guide Series about Gilbert attending the 75th reunion anniversary.
The rifle and the tablet @ the intersection of Benner's Hill Loop and Hanover Road (Pennsylvania Highway 116), on the right or west side of the road when traveling south on Benner's Hill Loop. To the left of the tablet is this 20-pounder Parrott which represents the battery. Parking is available all up and down the narrow road. Take care to not park on anything remotely green looking as Park Police will happily ticket you. I visited this site on Monday, July 1, 2013 on the 150th anniversary of the Battle of Gettysburg shortly after 1:00 PM, ED. As always, I used my trusty and oft abused Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
About the Inventor of the Parrott
In 1835, Captain Robert Parker Parrott, a West Point graduate, was appointed inspector of ordnance from the foundry. The next year, he resigned his commission and on October 31, 1836 was appointed superintendent of the foundry. It prospered under his tenure, and was the site of numerous experiments with artillery and projectiles, culminating in his invention of the Parrott rifle in 1860. During Parott's tenure, in 1843, the foundry also manufactured USS Spencer, a revenue cutter which was the first iron ship built in the U.S. The foundry's operations peaked during the Civil War due to military orders: it had a workforce of 1,400 people and produced 2,000 cannon and three million shells. Parrott also invented an incendiary shell which was used in an 8-inch Parrott rifle (the "Swamp Angel") to bombard Charleston. The importance of the foundry to the war effort can be measured by the fact that President Abraham Lincoln visited and inspected it in June 1862.
SOURCE
About the Foundry:
The Union version of this rifle was cast at the West Point Foundry out of Cold Springs, NY while the Confederate version was cast at the Tredegar Iron Works out of Richmond, VA. Tredegar was a major weapons manufacturer for the United States and state governments from 1848 to 1861, and then for the Confederacy during the war. The company was owned by Joseph Reid Anderson. The markings on their guns/cannons may be stamped "J.R.A. & Co.," or more often, "T.F.," generally without Anderson's initials prior to the war and with them on Confederate pieces. The firm also was called Tredegar Iron Works, but Tredegar Foundry was by far the most commonly used name.
Today, the foundry is a museum. The American Civil War Center at Historic Tredegar is the nation's first museum to interpret the Civil War from Union, Confederate, and African American perspectives. he Tredegar Iron Works was the Confederacy’s most important industrial complex during the Civil War. In peacetime, it supplied the vast expansion of the railroad industry; in war it produced the largest number of cannon in the Confederacy. Students are treated to a tour of the grounds learning about the manufacturing of iron, the people who worked here, the historic buildings on site and Tredegar owner Joseph Reid Anderson. SOURCE
From Wikipedia: The Tredegar Iron Works was a historic iron works in Richmond, Virginia, United States of America.[3] Opened in 1837, by 1860 it was the third-largest iron manufacturer in the United States.[4] During the American Civil War, the works served as the primary iron and artillery production facility of the Confederate States of America. The iron works avoided destruction during the Evacuation Fire of 1865, and continued production through the middle of the 20th century.
Today a National Historic Landmark District, the 22-acre site and remaining structures serve as the main visitor center for the Richmond National Battlefield Park of the National Park Service, as well as the location of a private museum, The American Civil War Center at Historic Tredegar. SOURCE
About the Gun
In the field, the 10- and 20-pounders were used by both armies. The 20-pounder was the largest field gun used during the war, with the barrel alone weighing over 1,800 pounds. SOURCE In 1862, the manufacture of the rifle cost $380 for a Union version and $550 for a Confederate version.
The 20 Pounder Parrott Rifle was one of the heaviest field artillery pieces of the American Civil War. It was highly accurate, cheap to make, and easy to operate. In hard-hitting and accurate counter-battery fire - the 20 Pounder Parrott had no match. However, it was soon discovered that Parrott Rifles, particularly the 20 pounders and larger were prone to bursting, killing and injuring many artillerymen. The cast iron design of these large rifles just couldn't contain the stresses of firing.
The 20 Pounder Parrott Rifle was one of the heaviest field artillery pieces of the American Civil War. It was highly accurate, cheap to make, and easy to operate. In hard-hitting and accurate counter-battery fire - the 20 Pounder Parrott had no match. However, it was soon discovered that Parrott Rifles, particularly the 20 pounders and larger were prone to bursting, killing and injuring many artillerymen. The cast iron design of these large rifles just couldn't contain the stresses of firing.By 1862 General Henry Hunt attempted to eliminate the 20 Pounder Parrott completely from the Army of the Potomac. He felt that these guns were nearly as dangerous to the gun crews serving them as to the enemy.
The 20 Pounder Parrott Rifle was one of the heaviest field artillery pieces of the American Civil War. It was highly accurate, cheap to make, and easy to operate. In hard-hitting and accurate counter-battery fire - the 20 Pounder Parrott had no match. However, it was soon discovered that Parrott Rifles, particularly the 20 pounders and larger were prone to bursting, killing and injuring many artillerymen. The cast iron design of these large rifles just couldn't contain the stresses of firing.Although the 20 Pounder Parrott had a questionable reputation, it served it's purpose on the battlefield. Parrott Rifles may not have been the best field guns, but they could be produced quickly and in quantity at a time when the Army was desperate for rifles, not necessarily the best rifles, but rifles. When the war was over they were not used again. SOURCE
About the Battery
Graham's Battery served as a member of Dance’s Battalion, one of 6 batteries which made up the battalion in Ewell's 2nd Corps artillery reserve. The battery was commanded at Gettysburg by Captain Archibald Graham. The Battery was Organized April 12, 1861 and mustered in on April 29, 1861. On April 9th, 1865, 1st Rockbridge Artillery, Captain Archibald Graham, surrendered 101 officers and men, thus concluding the battery's term, effectively mustering out the unit.
The tablet marks the position and actions of Graham's artillery battery on July 2, 1863 reads as follows:
Army of Northern Virginia
Ewell's Corps - Artillery Reserve
Dance's Battalion - Graham's Battery
Rockbridge Artillery
Four 20 pounder Parrotts
July 1 The Battery arrived on the field too late to participate in the engagements of the day. Was ordered to report to Lieut-Colonel H.P. Jones commanding Artillery Early's Division and moved into position on the left to the south and east of town.
July 2 Remained in position on the left firing occasionally
July 3 Remained in position during the day and rejoined the Battalion during the night.
July 4 Took up line of march to Hagerstown.
Ammunition expended 439 rounds - Losses not reported in detail
The rifles (incorrectly called cannons) are also identified in the NRHP nomination and narrative form.
One of 100 cast iron tablets designed by E.B. Cope marking positions of batteries and brigades along avenue system not otherwise marked by monumentation. Tablets designating artillery positions have 1-4 mounted cannons flanking them. Marks position of Graham's Rockbridge Artillery July 2-4, 1863.
Short Physical Description:
Cast iron tablet w/ raised inscription painted in contrasting color & mounted on fluted cast iron post. 4'4" high; 3.8' x 3.4' tablet, inscription narrates events associated w/ Battery during Battle. One cannon to left of tablet. Located at Benner's Hill, W side of avenue at N end.
Long Physical Description:
Cast iron tablet with raised inscription painted in a contrasting color and mounted on fluted cast iron post. 4'4" high. Cast by Calvin Gilbert. The inscription on the 3.8' x 3.4' tablet narrates the events associated with Battery during the Battle. One cannon is located to the left of the tablet. Originally with two cannon; one relocated to Evergreen Cemetery.
Source
1.
NRHP
2.
Stone Sentinels
3.
Virtual Gettysburg
4.
Draw the Sword
5.
Historical Marker Database