Well, that s/n is just a bit off what I was thinking - but, is there any possibility that it could actually be 388602? Worse mistakes have been made than reading an "8" as a "3", believe me.

If it is 388, with an originally crowned 26" barrel, you really do not want to cut it further!  Look under "Articles" on the home page, with reference to the s/n's of the (100 only made!) BoOF rifles.