Some time ago, I decided to mount a scope (Zeiss Conquest 4.5-14X44MC) on my Standard Springfield M1A. I ended up deciding to give the newer 4th Generation steel mount from Springfield Armory, given that I assumed it would work better with a Springfield rifle (a lot of other mounts were designed for M14's with mil-spec drop forged receivers). I tired mounting the scope myself with some low rings, only to have issues with it, given that I was always hitting to the left, and I could not adjust the scope far enough to compensate for this. I took it to a gunsmith, which remedied the problem for some time. However, I decided to get some higher scope rings so I could use that "U" shaped channel to see the iron sights. After I simply switched the rings (I did not adjust mount itself at all), I was having the same issue with being so far off to the left that I could not compensate for it (the dial on the scope would not turn that far). I ended up taking the gun back to the gunsmith, where some modification was done to the mount to try to make it work better with Springfield's cast receiver (the Gen 4 mount from SA looks pretty similar to the Sadlak mount).
I finally got back to the range not too long ago, and I was hitting so high that the scope could not be adjusted to compensate for this. The gunsmith must have also forgotten to use thread locking compound, as the mount came a bit loose. I later reinstalled the mount, but after taking it out today, I am now far off to the right.
Why are there so many problematic fluctuations here? I don't think that the scope itself would be to blame (it does not appear to be damaged), but I am wondering if Springfield's out-of-spec receiver has something to do with it. It is pretty irritating to get an expensive Zeiss scope, only to have these kinds of issues. I have removed the scope and mount from the rifle and I now use iron sights for the time being, but I am seriously toying with the idea of saving some money and getting a properly built M14 from Fulton Armory or LRB (I would just keep my Stanard M1A for blasting around with cheaper ammunition and iron sights).