FWIW
From R&D:
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"R&D DROP-IN CONVERSION CYLINDER, for Colt 1851 Navy
Now available for the Colt 1851 Navy (.36 Caliber Only !) (Steel Frame Revolvers Only !)"
"This R&D Conversion Cylinder is available for the Pietta and Uberti 1851 Navy reproductions only."
"Not available for the 1851 Colt US Marshall .44 caliber."
note: "For Colt revolvers, You must not use the conversion cylinder if the cylinder pin is not tight in the back of the frame. If there are any questions, you should seek assistance from a professional gunsmith."
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Good Luck.
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