I recently acquired a Model 37 round butt #329630 this is the butt number. It has a square cylinder release button. Very nice piece appears to be unfired or virtually unfired. Shows some wear from sitting in a drawer for many years. Some one has highlighted the sights with red and yellow paint. The job appears to have been done by some one knowledgeable as it is of good quality. I believe it was originally sold in Maine probably in the early or mid 60's Can anyone add to the information I have on this piece?