lMHO Blr it depends a lot on the size of the screw and materials they are made of but they should at least be evenly tightened and the bases should be tightened to around 20-25 inch pound, l like to use 1 piece bases because the base should be more rigid as be lined up straight
l would also advise to bed the bases with JB weld or similar, like what this guy is doing
https://www.youtube.com/watch?v=wrX73goySlwl do it a bit differently as l basically glue the base to the action not wanting the base to ever be removed and put the screws in straight away to line it all up but not tightening the base screws to 20-25 inch pounds till the JB weld cures, obviously the screws are greased so they do not get glued while the JB weld is curing and the base is tightened just enough to make it flush before curing has happened
this is what works for me
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