R.Marshall,
Not knowing where you live, I don't know if there are any gunsmiths in your area. I think if you can find one with headspace gages, he can determine the correct chambering of your rifle. If it is 6.5x57, as I think, it will close on a 6.5x57 go gage, but a 6.5x55 should not. Headspace gages for 6.5x55 are more common than 6.5x57( in the US); if the bolt will close on a 6.5x55 no go gage it is likely 6.5x57, but if it won't it is likely 6.5x55. I hope this doesn't confuse matters more.
Mike
