These sights tend to pop up on eBay from time to time (complete or parts) so just keep an eye out.
Interesting that the sight is a Lyman 48M. The "M" designation sights were designed for use on various Mausers. You will typically see the 48S model installed on 1903's. Do you mind posting a few photos of the rest of the rifle? Is it a Springfield, RIA, or Remington?
Here is a high number RIA that I previously owned with a Lyman 48S rear sight and 17A front globe sight installed. The small circular brass can with the orange Lyman label shown in the photo contained a handful of alternate front sight inserts for the 17A.
Interesting that the sight is a Lyman 48M. The "M" designation sights were designed for use on various Mausers. You will typically see the 48S model installed on 1903's. Do you mind posting a few photos of the rest of the rifle? Is it a Springfield, RIA, or Remington?
Here is a high number RIA that I previously owned with a Lyman 48S rear sight and 17A front globe sight installed. The small circular brass can with the orange Lyman label shown in the photo contained a handful of alternate front sight inserts for the 17A.