According to the book "BILL RUGER AND HIS GUNS". In 1968 they started using a 130 prefix, 130-00000 to 130-49998. The #3's were numbered 130-50000 to 70344 until 1980. From 1980 until discontinued about 1986 the numbers were mixed with #1's. The #1's continued with 131-00000to 54116, 132-00000 to 99999, 133-0000 on. Not all serial numbers were used.
Again my source is "BILL RUGER AND HIS GUNS" copyright 1996
ISBN # 0-684-80367-4
I hope this helps.
Jim