Scope Base Bedding Question

[Doc. Holiday]

I have been searching around and I still haven't found a clear answer as to why people do not put bedding material (JB weld, Devcon, etc) on both sides of the scope base. Often I am seeing people only bed the side that is closest to the shooter and not the front. Why is that?

[Canonshooter]

IMO, you need to do the entire base.

From what I have read, the top-rear of the Remington 700 receiver is hand polished to remove tooling marks. If you install only the two front screws, there will be a small gap between the bottom-rear of the base and the top of the receiver.

FWIW, I bedded mine without the use of release agent on the mount and receiver, but on the screws so they could be removed, cleaned and then torqued down. Here is the method I used;

https://www.murphyprecision.com/Page/Scope_Base_Bedding

Using this method, I ended up with about 10 MOA of elevation using a 20 MOA base. If using a 0 MOA base, I might be more inclined to do just the rear and only tighten the front two screws to set the base in the JB Weld (as opposed to the two center screws as per the Murphy method).

[SomeOtherGuy]

Bedding is to insure a good fit when scope rail and receiver don't match. This happens due to dimensional inconsistencies, which 99% of the time are in the receiver, not the scope base. Not all combinations need bedding in the same places. If they did, the base manufacturer would account for that and none of them would need bedding!

How does this address your question? Well, you compare a clean/dry base to the receiver and determine where gaps exist. If the gaps exist only at one end, you bed that end, only. If you try to bed both ends when only one has a gap, you will have very minimal bedding left at the end without a gap, and you have a strong chance of distorting the rail alignment. I once accidentally turned a 0 MOA rail into a -30 MOA rail (counterproductive) through poor bedding. I later fixed this by removing the bedding and starting over, and got my intended 0 MOA rail alignment.

Anyway, if people bed only the rear, there's at least a chance they know what they are doing and that only the rear had a gap.

[Doc. Holiday]

Good to know. Are the gaps just a visual inspection or is there another way of checking?

[SomeOtherGuy]

Viewing the gaps, if any, is an easy and adequate way of checking. If you are a skilled machinist or have access to automatic measuring equipment (some shops have a laser measuring tool where you put a part on a granite slab and the computer uses a laser to measure all dimensions precisely) you could probably do a more precise measurement that way. I'm not in that category!

Basically, viewing gaps and fixing any is adequate to keep the rail from being installed with a noticeable bend that might damage your scope or affect its adjustments. That's "good enough" for most purposes, even things like F-class. Someone who's going after extreme precision, like a serious unlimited-benchrest shooter, would probably want more advanced methods to get more precision. At that point you need a real machinist-gunsmith who's been doing this a while. But that is outside of typical M4C focus.

[Doc. Holiday]

Gotcha. Ya I'm just a guy in his garage trying to do a 1 MOA or better if possible precision rifle. This is more of a budget project that I plan on swapping out for better parts in the future.