Just bought a Mosin-Nagant 91/30, did not get it to really collect, but to use at the range. I want to mount a scope so I am going to use one of the mounts available online which replaces the rear sight. Looking at the Leapers UTG tri-mount had good reviews. My question is that by using this mount, thus avoiding altering bolt to clear scope, I have to get one with a long eye relief. What I don't know is approximately how long that relief should be. Hard to measure without the scope. Does anyone have any experience with this. Most LER scopes I have seen are about 5". Does this mean that the max distance my eye can be from the scope is 5" for a clear view? Don't have much experience with this. Thanks