I'm in the process of getting my light weight barrel and grenade ring/repro moderator packed up and ready to go to ADCO for the appropriate machine work.  Before I send it off, I have a question about my fsb.  On the right side, the following characters appear.  First is an F, then RI in a circle, then a 4.  I bought the barrel/fsb assembly attached to an A1 upper, which I know doesn't men a a thing, I just want to be sure this is the "correct" fsb as I was going to have ADCO also remove the flashing and reparkerize it.  Am I gtg here, or do I need another fsb?  Thanks to all, once again.  I checked the usual sources, but still ng.

Those markings are forge codes. The F doesn't signify that the FSB is F-height. F-marked FSB's will have the F on the left side.

For an XM177E2 the FSB should be smoothed of flash & have no markings or codes on it up till the early 70's per Ekie's carbine guide at the top of the forum.

Thanks guys.  I will ask ADCO to remove all ID and flash from the fsb.

Don't forget the bayonet lug, I did, and then found out later that XM-177's didnt have them.
Just a reminder to not do what I did.

Check, thanks.