I would agree the initials on the butt plate most likely just belong to someone after the US ownership. I am going to take a stab at the SRS listing and say the gun next to mine was sent to First Company, Fourth United States (V)?????? Infantry. That is as close as I can guess except for the V. Am I close? I will try to shoot a photo of the sight base. I had not thought to look at that area. That older guy I bought this gun from knew that it was a very nice gun and carbine but I don't know if he knew it was an 1898 period upgraded to 1899. I believe from what I have just started reading that there are not many 1898 carbines because not many were made and in only a short run but also all were used quickly and maybe heavily. Don't know what US engagements were happening in or around this time fore the 1898's to be used in. Can someone on the forum perhaps enlighten us(me). Thanks for everyons's comments. These guns are fun it seems because they were used and produced during interesting times in US history. PS, can someone perhaps explain why one gun in the SRS records would be listed and the very next one not?????