I recently acquired a 1901 Remington Rolling Block 7 mm. This is supposed to be the 7x57, BUT maybe not exactly. This model was built for several nations' armies, and this rifle has a bayonet lug. I have read that this model MAY have excessive headspace and require modified brass for loading safely and shooting. Other sources say they fire standard sized 7x57 ammo. I took the gun to a local gunsmith who superficially looked it over, said it looked very good and safe to fire, but did not specifically measure headspace even though that was my specific question. I do know that this gun should be loaded with cast bullets and at much lower pressure (velocity) than modern 7x57 weapons. I have read about methods of neck sizing with a .30 caliber die, then partially neck sizing only with the 7x57 die to create a false shoulder, loading the ammo and firing to produce fire-formed brass to then be loaded for this gun. This process is described as being hard on case necks, requiring frequent annealing of the necks. One source also indicated that this neck sizing requires a neck sizing die while others imply that it can be done with a regular die so long as you do not size the entire case. This whole process seems like more than I may want to tackle, but I hate to give up without trying. I already have 7x57 reloading dies and brass as I have loaded (much hotter) ammo for a Ruger #1 in this caliber for years. I may not ever shoot this gun a lot, but would really like to shoot enough to determine point of aim and to kill a deer with it. The rear sight is a ramp for elevation which also can be raised for greater distances. There are numbers on the left side of the ramp from 1 through 5, and on the elevated portion from 6 through 19. I wondered if this represented ranges from 100 to 1900 yards? Any reliable help with info about safely shooting this gun would be appreciated.

If you are nervous putting a light loaded round in and shooting it to see how the case comes out do or have done a cast of the chamber.

Better yet, take it to a knowledgeable gun smith and have him make a determination and check it for being safe. I would not shoot any round out of the gun til it has been checked out if you are not sure about the caliber.