If milled off at the factory - it doesn't affect value at all. Many rifles left with scope rails milled off (I have one such rifle in my own collection, also a VOPO). It simply means that the rifle didn't meet the highest accuracy standards; they simply milled off the rail to prevent the temptation of mounting a scope to a slightly sub-standard rifle. By the finish and milling marks, you should be able to tell if the work was done in the factory or not. Usually rifles with milled off rails are late rifles. Your is 1944 with a pretty early suffix, but some receivers were set aside and completed later in the war. If not as accurate as other rifles, that might explain why it was potentially assembled later. If it was milled post war, it pretty much makes the rifle a parts gun/shooter.

Claus Espeholt has a good website and serial number study on these rifles and often there is a pattern in production/finishing.