I wish to purchase, have built or convert a rifle in one of the .40 calibers built on a standard length Mauser action. I do not want to reload ammo but wish to be able to purchase ammo from gun dealers or stores. Which caliber could be built on a standard length Mauser. .404 Jeffery, .416 Remington Mag., or are there other choices? I have ruled out the .425 Express as commercial ammo in not available. I have also more or less ruled out the .416 Taylor as ammo for this caliber is not readly available. Also I have a chance to buy a 10.75x68mm Mauser with a .425 bore. Could this rifle be converted to a .404 Jeffery? I believe the bore on the Jeffery is .424 while the bore on the 10.75x68 is .425, how much would the .001 difference in bore make? I also have the opportunity to buy a .425 express but do not know what the bore is for this caliber. Does someone know what the bore is on a .425 Express and if it can be converted to a .404?