riflescope adjustment

on my .444s marlin rifle i mounted a scope a burris red-dot 3-9 its an older type however,when sighting in i am 5 -7 inches high at 100 yrds off the bench and am the lowest setting on the rear sight , should i leave it there or say for a 150 yrd shot guess where to point like middle of deer body and hope , can i buy a shim for the front of my scope i have a one piece weaver scope mount on it now . shims a hoy

I guess you're talking about your elevation adjustment being all the way down. Shoot your gun with the ammo you're using and the iron sights or a different scope. If your point of impact is okay, you have a problem with your scope. Shimming a one piece base may work with several shims, but it's not a great way of doing it. If it is your scope, I wouldn't trust it to hold zero.