Make: Whitneyville Armory (Eli Whitney Jr.)

Model: U.S. Navy “Plymouth” Rifle (Whitney Model 1861 Naval Rifle)

Serial Number: 6510

Year of Manufacture: Circa 1861–1864

Caliber: .69 Caliber Rifled Musket

Action Type: Single-Shot Percussion Rifle

Markings: The lockplate is marked “U.S. / WHITNEY-VILLE” ahead of the hammer with an eagle motif and “1863” to the rear. The breech is stamped “6510.” The barrel bears correct “V / P / Eagle Head” proofs. The buttplate tang is marked “U.S.,” and the stock has an inspector’s cartouche and sub-inspection marks.

Dahlgren Bayonet: Ricasso marked “AMES MFG. CO / CHICOPEE / MASS” and “U.S.N. / D.R. / 1864.”

Naval Saber Bayonet: Ricasso marked “C. ROBY / W. CHELMSFORD / MASS” with “U.S.N. / D.R.” and serial number “5671.”

Barrel Length: 34”

Sights / Optics: Front blade doubles as a bayonet lug. Rear is a ladder sight graduated 100–1000 yards.

Stock Configuration & Condition: Full-length walnut with brass fittings. Moderate dings and compressions but no cracks. Brass has deep, unpolished patina. Fit is tight. Rates Very Good.

Type of Finish: Originally Armory Bright, now a semi-bright and smooth patina mix.

Finish Originality: Original

Bore Condition: Bright with sharp rifling and scattered light erosion. In this writer’s opinion, the bore rates 8.5/10.

Overall Condition: Strong mechanical function and sharp markings. Metal shows a mix of semi-bright surfaces and smooth aged patina. Rifle rates Very Good to Fine for a Civil War naval arm.

Mechanics: Action is functional with secure hammer engagement. Nipple is intact; ladder sight locks properly. As with all used firearms, a thorough cleaning may be necessary.

Accessories:

Ames Dahlgren Bayonet – 12" blade, brass hilt, slab grips. Designed for extreme close-quarters combat in boarding actions and amphibious assaults. Includes original brass-mounted scabbard.

Roby Saber Bayonet (Serial #5671) – Curved blade with full-length grooved brass hilt and leather scabbard. Moderate freckling present.

Our Assessment: This is a rare and desirable Civil War U.S. Navy arms set featuring the Whitney Plymouth Rifle and both bayonets it was issued with: the Ames Dahlgren Bowie and the Roby Naval Saber. This model was designed by Admiral John A. Dahlgren specifically for maritime warfare—heavier than standard muskets and chambered in .69 caliber for maximum stopping power. These were issued to Union sailors and Marines tasked with boarding actions and amphibious landings.

The Dahlgren bayonet was essential to that mission—its brutal Bowie-style profile made it a versatile weapon and tool in the close quarters of deck combat and coastal assaults. Standard bayonets were simply too fragile or narrow. The inclusion of both the Dahlgren and the Roby, each with scabbards, makes this a complete and original fighting rig.

Matched naval sets like this rarely survive intact. If you're a collector of Civil War weapons, edged arms, or U.S. Navy martial history, this offering stands at the intersection of innovation, purpose, and scarcity.