This replica is an excellent example of a 3-inch ordnance rifle and naturally, is in terrific shape: its limber, carriage, barrels and all other things weaponry are in terrific condition. Some of those components look to be authentic. These cannons are much smaller than the other cannons used here in 1863 such as the accompanying 10-pounder Parrott rifle also located here or the Napoleons. These weapons are quickly identifiable as the tubes are black, very smooth, and almost always in terrific shape and represented at the time, some pretty serious weapon technology. Their trunnions are sometimes devoid of markings, however some examples have stamps on both trunnions. They always read the same: From the guns perspective, the left trunnion reads Patented Dec. 9, 1862 and the right trunnion reads, Phoenix Iron Co.. Their tubes do not have the breech band seen in the similar looking Parrotts, which distinguishes the two. The 3-inch carriages and limbers are also always equally pristine. This model was also mass-produced by the Confederates as well, but not nearly as well made as their Union counterparts. The stamps on the outer muzzles of these rifles are almost always legible and often times pristine which allows tracing back the manufacturing origins a snap. I think this is due to the deep incising of the registry inscription/information along the muzzle as compared to other cannons which were much more shallow in their engraving. This is the first one of these rifles I have found without a stamp and after a brief investigation I confirmed my suspicion this was in fact a replica.
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 replace 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 
Raine's Lee Artillery Battery tablet are located @ the very end of Benner's Loop, at the cul-de-sac. Wrap around the circle and start heading north, back to the main road, Hanover Road. The rifle is on the right side of the road or at the 9 o'clock position on the circle if pointing north toward Hanover Road. Parking is available all up and down the narrow road and especially at the cul-de-sac. If facing the tablet, to the right is a replica 10-pounder Parrott rifle and to the right, a replica 3-inch ordnance rifle. Take care to not park on anything remotely green 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 @ 1:12 PM, EDT. As always, I used my trusty and oft abused Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
About the Foundry
Had this gun been authentic it would have been made at the Phoenix Iron Works, so, what harm is there in learning about that site? The Phoenix Iron Works (1855: Phoenix Iron Company; 1949: Phoenix Iron & Steel Company; 1955: Phoenix Steel Corporation), located in Phoenixville, Pennsylvania, was a significant manufacturer of iron and related products during the 19th century and early 20th century. Phoenix Iron Company was a major producer of cannons for the Union Army during the American Civil War. The company also produced the Phoenix column, a significant advance in construction material. Phoenix Iron Works is a core component of the Phoenixville Historic District, a National Register of Historic Places site and in 2006 was recognized as a Historic Landmark by ASM International. SOURCE & SOURCE
About the Gun
The second most common rifled field artillery in both Armies generally, and the most common on the Maryland Campaign, the 3 inch Ordnance gun was made of hammer-welded, formed, machined iron. It was popular because of its accuracy and reliability, at least those examples built in Federal shops. Less precise machining and lower-grade iron gave their Confederate counterparts more trouble. Those built by the firm of Burton and Archer were know to be problematic. The 3-inch rifle normally fired Hotchkiss or Schenkel shells that weighed between 8 and 9 pounds. In an emergency it could use 10-pounder Parrot ammunition. It could also be used to fire cannister but, as a rifle, was not as effective with this as howitzers or Napoleons. The maximum range of this weapon was 1830 yards, with the barrel/tube Length 69 inches, the bore 3 inches (hence the name) and the total combined weight (already mentioned above), approximately 1720 pounds. Johnson, Curt & Anderson, Richard C., Artillery Hell: Employment of Artillery at Antietam, College Station, TX: Texas A&M University Press, 1995; and
Schwartz, Peter, Artillery at Gettysburg online. SOURCE & SOURCE.
About the Battery
The Lee Artillery Battery served as a member of Latimer's Battalion, Johnson's Division - Ewell's 2nd Corps. The Battery was commanded by Charles I. Raine. who was killed by a solid shot at Mine Run, Virginia, serving with Andrews Battalion on November 29, 1863.
Lee Light Artillery was organized at Lynchburg, Virginia, in May, 1861. This unit was active in Lee's Cheat Mountain Campaign and Jackson's Valley operations, then served in J.W. Latimer's, R.S. Andrews', and C.M. Braxton's Battalion of Artillery, Army of Northern Virginia. It fought with the army from the Seven Days' Battles to Cold Harbor, then participated in Early's Shenandoah Valley Campaign. The battery took 90 men to Gettysburg and surrendered at Appomattox with 12. It was under the command of Captains Pierce B. Anderson, William W. Hardwicke, and Charles I. Raine. SOURCE
The tablet marks the position and actions of Raine’s Lee Artillery Battery on July 2-4, 1863. The principal reason for the tablet's placement at this position were for the events on July 2 when this Battery engaged Union forces at Culp's Hill. Culp's Hill (N 39° 49.206 W 77° 13.220) is .54 miles southwest or 219° from this position. SOURCE The marker reads as follows:
Army of Northern Virginia
Ewell's Corps - Johnson's Division
Latimer's Battalion - Raine's Battery
The Lee Battery
Two 20 pounder Parrotts - one 10 pounder Parrott
and one 3 inch Rifle
July 2 The 10 pounder Parrott and 3 inch Rifle took position here about 4 p.m. and were engaged in the severe cannonade that lasted over two hours. They also aided in supporting the attack of Johnson's Infantry on Culp's Hill and did not retired to the rear until dark. The 20 pounder Parrotts took an active part in the cannonade from their position some distance in the rear of the other guns.
July 3 The 20 pounder Parrotts were actively engaged in the great cannonade
July 4 Withdrew from the field with the Battalion.
Losses - Wounded 8 - Horses killed 3
The rifles (incorrectly called cannons) are also identified in the NRHP nomination and narrative form. The pertinent information is highlighted with red font.
From the Nomination Form:
Civil War tablet that marks position of Raine's Lee CS Battery, known as "The Lee Artillery", July 2-4, 1863. Narrates events associated with the Battery during Battle of Gettysburg.
Short Physical Description:
Tablet w/ 2 cannon. Cast iron tablet, 3'8" x 3'4", with raised inscription painted in a contrasting color and mounted on fluted cast iron post. All 4'4" H. Cannon located left & right of tablet. Tablet cast by Calvin Gilbert, founder.
Long Physical Description:
Located at Benner's Hill, west side of avenue at road end.
My Sources
1. NRHP Nomination Form
2. Stone Sentinels
3. Virtual Gettysburg
4. Draw the Sword
5. Historical Marker Database