I'll be a little bit general in years because there seems to be some conflicting information when researching these things on the web, and that is where I got my info. I've tried to piece it together, but may not have it correct. Initially the Big Bore was only made in 375 win and came out about 1978 -1979. The serial numbers began with BB, all were top eject, and you could not get the raised stock. In the early 1980's the 307 and 356 win were also added to the big bore options. About 1983 - 1984 they used the XTR designation, which was likely mostly marketing, but indicated supposedly a better metal finish and better wood, including the checkering yours has. The raised stock was an option. By 1985 or 1986, the XTR was dropped and the checkered wood was no longer available. Since yours has the XTR stamp, and the raised stock and is AE, that would put it about 1983 or 1984. Some say only 1983 for the ones in 375 win. Its all confusing to research since there seems to be no official records, and there is conflicting info on the web. For instance, I've read in some places that the 375 was never made in AE, and other places say it was made in AE. Yours pics clearly settle that. I've read that all big bores were dropped from production about 1988. You can also read that about 19,000 were made in 375 in AE. If that is correct, your serial number would seem to put it later than 1983. But then the info concerning stock availability and XTR designation becomes contradictory. Confused yet?