I’m not a gunsmith, but I swap a fair amount of scopes…some rifles stay put more than others and a few rotate around often.
In my experiences I’ve had no issues with the long term mounting by doing the following:
-Use quality mounts and rings built for the application you intend to use them for. I’m not brand loyal or specific, more avoid no name unknowns as the quality is more random and the insert style rings that fit all diameters of scopes are definitely out for me.
-Always use a torque wrench and use the recommended settings for your particular combination, everytime, period. Over tightening screws without one is easy and can destroy threads or a scope. Loose screws and you’ll spend a bunch of money on ammo and never group (in one case I saw a guys scope fall off..).
-Make sure you use the right screw and it has the depth to accept it. Wrong thread and nothing good can happen so make sure they match threads first. Too short a screw and it can strip out, too long and it can either bottom out and leave the base loose (sometimes it can look seated and tight but it’s the other screw packing the load) or the other problem is it could damage and/or restrict the motion of the bolt. Long story short, use the right fasteners. This is very important if installing used rings or mounts.
-I like thread locker, but whatever floats your boat. One thing to consider if using it; if reusing any screws that have had it applied previously (used rings/mounts/screws/receivers) is that the threads need to be cleaned of any remaining product. It will leave a reside that will give false torque thresholds which can create problems. So you would need to plan to do that as it likely will require specific tooling to do as most guns don’t use generic hardware store threads. Note that using it will not correct the use of incorrect torque or wrong fasteners, it isn’t a magic elixir but I don’t subscribe to the idea that using the correctly rated thread locker will hurt anything, I think it’s just added insurance.
-An alignment bar is a great tool, as are the 2 pointed bars, they will both aid in aligning everything which is the desired outcome. Misaligned mounts can at best require considerable internal adjustment and at worst easily permanently destroy a scope (regardless of brand). Getting them as aligned as possible is easier than down stream corrections that can cause later problems if removed and remounted or the potential damages to the scope by not doing it. I’ve seen incorrect mounts (new out of the box) not fit the intended application be installed and kink a scope tube (not me, a local LGS at the time); if they had checked alignment they never would have put the scope in the rings, instead they plodded on and it wound up in the garbage can. Also, lapping misaligned rings would not only require more work but if removed and then remounted will likely create misaligned lapped rings so it’s worth the time to align everytime in my opinion.
-Lapping will provide an even clamping surface and it can be surprising sometimes even using quality rings on a quality rifle so can be worth doing. Even if the rings are factory matched to the thousands of an inch or one piece, they weren’t line bored/honed mounted on your rifle. Production tolerances exist and lapping will match these various parts together so you could benefit from it for multiple reasons but if you lap them I would also recommend to lightly chamfer the edges as they can get sharp. The first time I did this I scratched my scope and was not happy, now if I do it I chamfer and don’t have this outcome. Another thing that’s never really warmed up to me about it but I have no direct evidence from it is by lapping you are exposing raw aluminum and using it under the right conditions (i.e.: salt water) could lead to corrosion so on rifles I intend to use in that kind of environment I don’t lap, but I do ensure they are aligned as good as possible or use a design that eliminates this concern.
-After using the Optiloc Sako rings with their plastic orbital inserts I’ve gravitated towards this design more often than not and have been very happy with every outcome. Burris Signature’s and their XTR line also use this design. They are non marking, self centering and can provide cant or correction from using +/- inserts if needed/required. If there’s a con to using this type of design I’ve yet to see it but YMMV.
No doubt others have more experience than me but this has worked for me so far.