Good Evening Hans,
Thanks for writing and posting your photo's. Based on the information I have in my files, your revolver Serial No 128529, was manufactured in January 1865 and the Conversion No. 3665, with the Rollin White Patent was part of the April 1, 1869 delivery of the Kittredge contract for these conversions from Smith & Wesson, with Remington performing the actual work on the conversion.
The proper cartouche for this revolver would be "RPB" attributed to an unidentified “Principal Sub-Inspector”. This party inspected at Remington very late in the War. He also inspected Rogers and Spencer revolvers at Utica, New York, in early 1865, suggesting that he was also serving at Remington's Utica Armory.
RPB has been incorrectly identified as Robert P. Barry, an Ordnance Department Officer during the Civil War.
I trust that you find this information usefull and we encourage you to join the Remington Society of America.
Best regards,
Mike Strietbeck
V.P. Remington Society of America